A cross-lagged longitudinal MZ discordant twin design. This model can take account of relationships among differences across traits at time one, and then examine the distinct hypotheses that increments in trait1 drive subsequent change in that trait in the future, or, importantly, in other traits.


Varroa destructor on the head of bee pupa.


An illustration of a  Manhattan plot  depicting several strongly associated risk loci. Each dot represents a  SNP , with the X-axis showing genomic location and Y-axis showing  association level . This example is taken from a GWA study investigating  kidney stone disease , so the peaks indicate genetic variants that are found more often in individuals with kidney stones.


GWA studies typically identify common variants with small effect sizes ( lower right ). [ 7 ]


Example calculation illustrating the methodology of a case-control GWA study. The  allele  count of each measured SNP is evaluated—in this case with a  chi-squared test —to identify variants  associated  with the trait in question. The numbers in this example are taken from a 2007 study of  coronary artery disease  (CAD) that showed that the individuals with the G-allele of SNP1 ( rs1333049 ) were overrepresented amongst CAD-patients. [ 15 ]


Illustration of a simulated genotype by phenotype regression for a single SNP. Each dot represents an individual. A GWAS of a continuous trait essentially consists of repeating this analysis at each SNP.


Full 2D epistatic interaction maps point to epistatic signal [ 22 ]


Zoom in a full epistatic map for an Arabidopsis phenotype [ 22 ]


Regional association plot, showing individual SNPs in the  LDL receptor  region and their association to  LDL-cholesterol  levels. This type of plot is similar to the Manhattan plot in the lead section, but for a more limited section of the genome. The  haploblock structure  is visualized with colour scale and the  association  level is given by the left Y-axis. The dot representing the rs73015013 SNP (in the top-middle) has a high Y-axis location because this SNP explains some of the variation in LDL-cholesterol. [ 32 ]


Relationship between the minor allele frequency and the effect size of genome wide significant variants in a GWAS of height.


Location of Överkalix, Sweden


The two graphics illustrate sampling distributions of polygenic scores and the predictive ability of  stratified sampling  on polygenic risk score with increasing age. + The left panel shows how risk—(the standardized PRS on the x-axis)—can separate   'cases'   (i.e., individuals with a certain disease, (red)) from the   'controls'   (individuals without the disease, (blue)). The y-axis (vertical axis) indicates how many in each group are assigned a certain score. + At the right panel, the same population is divided into three groups according to their predicted risk, i.e., their assigned score, as  high  (red),  middle  (gray), or  low  (blue). The y-axis shows the observed risk amounts, where the x-axis shows the groups separating in risk as they age—corresponding with the predicted risk scores.


An early (2006) example of a genetic risk score applied to Type 2 Diabetes in humans. [ 19 ]  The authors of the study concluded that, individually, risk alleles only moderately identify increase-of-risk of disease; but identifiable risk is "multiplicatively increased" when information is combined from several known risk polymorphisms. Using such combined information allows for identifying subgroups of a population with odds for disease that are significantly greater than when using a single polymorphism.


Predicted vs actual height using a polygenic risk score


PGS predictor performance increases with the dataset sample size available for training. Here illustrated for hypertension, hypothyroidism and type 2 diabetes. The x-axis labels number of cases (i.e. individuals with the disease) present in the training data and uses a logarithmic scale. The entire range is from 1,000 cases up to over 100,000 cases. The numbers of controls (i.e. individuals without the disease) in the training data were much larger than the numbers of cases. These particular predictors were trained using the  LASSO  algorithm. [ 17 ]


DNA transposons, LTR retrotransposons, SINEs, and LINEs make up a majority of the human genome.


pBLU is a 5437bp vector plasmid. This vector contains the origin of replication sequence, the restriction enzyme cut site, lacZ gene, and an ampicillin resistance gene.


Examples of mobile genetic elements in the cell (left) and the ways they can be acquired (right)


Transposition of target sequence into recombination site in DNA by Transposase. Replication of the transposable sequence starts to occur when transposase cuts single strands on opposite sides of the dsDNA. The replication is completed in the transposon complex and excised to target sequence for recombination.


Retrotransposon mechanism that uses reverse transcriptase to change mRNA transposon back into DNA for integration.


ColE1 replication control


"Cut and Paste" transposable element mechanism of excision and insertion into target site.


Rolling circle replication of a circular DNA plasmid.


Self-synthesizing transposition mechanism for Polintons.


Spotting on maize kernels shows activation of DNA transposons.


Barbara McClintock  was the first to discover the existence of DNA transposons in maize plants at  Cold Spring Harbor Laboratory . She was awarded the  Nobel Prize in Physiology or Medicine  in 1983.


Diagram illustrating the role of insertion sequences ("IS") in a composite transposon


Genetic structure of murine LINE1 and SINEs. Bottom: proposed structure of L1 RNA-protein (RNP) complexes. ORF1 proteins form trimers, exhibiting RNA binding and nucleic acid chaperone activity.


ORF2 protein (exhibiting  reverse transcriptase  and  endonuclease  activity) from human  LINE-1 .


Genetic structure of murine LINE1 and  SINEs . Bottom: proposed structure of L1 RNA-protein (RNP) complexes. ORF1 proteins form trimers, exhibiting RNA binding and nucleic acid chaperone activity.


Mechanism of target-primed reverse transcription (TPRT) , directly at the site of integration: L1 RNP recognize AAAATT hexanucleotides and ORF2 endonuclease activity cleaves the DNA first-strand. L1 polyA tail associate with TTTT overhang and the host DNA is used as a primer to initiate reverse-transcription. ORF2 probably also mediate second-strand cleavage and attachment of newly synthesized cDNA to the DNA template, using again host DNA as a primer for second-strand synthesis.


A.  Genetic structure of LTR-retrotransposons (gypsy-type).  B.  Mechanism of retrotransposition, occurring inside viral-like particles in the cytoplasm. Reverse transcription initiates at a host tRNA primer binding site (PBS) located immediately downstream of the 5’LTR. The newly synthesized minus-strand cDNA copy of the 5’LTR is then transferred to the 3’LTR and used as a primer for reverse-transcription of the entire minus-strand sequence. An RNase H-resistant polypurine tract then serves as a primer for plus-strand synthesis of the 3’LTR and complementary PBS. The newly synthesized plus-strand PBS then associates with the already-synthesized minus-strand PBS, and double-stranded cDNA is finally produced. Double-stranded cDNA is then transferred to the nucleus by integrase proteins, and a new copy is integrated into the genome.


Diagram of a bacterium showing chromosomal DNA and plasmids (Not to scale)


There are two types of plasmid integration into a host bacteria: Non-integrating plasmids replicate as with the top instance, whereas  episomes , the lower example, can integrate into the host  chromosome .


Overview of bacterial conjugation


Electron micrograph  of a DNA fiber bundle, presumably of a single bacterial chromosome loop


Electron micrograph of a bacterial DNA plasmid (chromosome fragment)


A schematic representation of the  pBR322  plasmid, one of the first plasmids to be used widely as a  cloning vector .  Shown on the plasmid diagram are the genes encoded ( amp  and  tet  for  ampicillin  and  tetracycline  resistance respectively), its origin of replication ( ori ), and various  restriction sites  (indicated in blue).


Insulin


Formation of a prophage


Phylogenetic tree  of  marsupials  derived from retroposon data [ 1 ]


Simplified representation of the life cycle of a retrotransposon


Genetic structure of murine LINE1 and SINEs. Bottom: proposed structure of L1 RNA-protein (RNP) complexes. ORF1 proteins form trimers, exhibiting RNA binding and nucleic acid chaperone activity. [ 16 ]


Schematic of retrotransposon propagation through the genome.


Piwi-interacting RNA's structure


Genetic structure of human and  murine  LINE1 and SINEs.


Metaphase spread of a cell line showing a  ring chromosome  (R) and several non-sister chromatid exchanges (SCEs), some of which are indicated by arrows.


Scheme of a sister chromatid exchange. The ends of the chromatids are reversed in the lower area.


Figure 1. Mechanism of SB-mediated transposition.   Top line:  A transposon, defined by the mirrored sets of red double arrows (IR/DRs) is shown as contained in another DNA molecule (e.g., a plasmid shown by the blue lines).  The transposon in this example harbors an expression cassette consisting of a promoter (blue oval) that can direct transcription of the gene or other DNA sequence labeled “genetic cargo”.   Middle lines:   Sleeping Beauty  (SB) transposase binds to the IR/DRs as shown and cuts the transposon out of the plasmid (the cut sites are indicated by the two black slashed lines in the remaining plasmid)   Bottom two lines:  Another DNA molecule (green) with a TA sequence can become the recipient of a transposed transposon.  In the process, the TA sequence at the insertion site is duplicated.


Figure 2: Structural features of SB transposase.  The 360-amino acid polypeptide has three major subdomains: the amino-terminal DNA-recognition domain that is responsible for binding to the DR sequences in the mirrored IR/DR sequences of the transposon, a nuclear localization sequence (NLS), and a DDE domain that catalyzes the cut-and-paste set of reactions that comprise transposition.  The DNA-recognition domain has two  paired  box sequences that can bind to DNA and are related to various motifs found on some transcription factors; the two  paired  boxes are labeled PAI and RED.  The catalytic domain has the hallmark DDE (sometimes DDD) amino acids that are found in many transposase and recombinase enzymes. In addition, there is a region that is highly enriched in glycine (G) amino acids.


Figure 3. Construction of SB transposase.  Step 1: Schematic of extinct  Tc1/mariner -like transposons in modern salmonid genomes; x, missense mutations; S, termination mutations; F, frameshift mutations; G, major gap/missing amino acids.  Step 3: Elimination of the gap (G) and termination and frameshift mutations.  Step 4: reconstruction of the bipartite NLS sequence (orange underline).  Steps 5–8: reconstruction of the N-terminal DNA-binding domain (orange underline).  Steps 9–10: reconstruction of the catalytic domain (orange underline) including the signature DDE residues (green boxes).


Figure 4: Uses for the  Sleeping Beauty  transposon system


A  bacterial DNA transposon


A . Structure of DNA transposons (Mariner type). Two inverted tandem repeats (TIR) flank the transposase gene. Two short tandem site duplications (TSD) are present on both sides of the insert.   B . Mechanism of transposition: Two transposases recognize and bind to TIR sequences, join and promote DNA double-strand cleavage. The DNA-transposase complex then inserts its DNA cargo at specific DNA motifs elsewhere in the genome, creating short TSDs upon integration. [ 16 ]


Structure of the Tn5 transposon, with insertion sequence flanking a cassette of genes, in this case drug resistance genes.


Sleeping Beauty Transposon System. Transposase enzyme can be expressed in  cis  or in  trans  to the gene cassette.


Process of analysis of DNA flanking a known insert by PCR.


Process of analysis of DNA flanking a known insert by plasmid rescue.


The white morph of the  monarch  in  Hawaii  is partly a result of  apostatic selection . [ 25 ]


The  humpback anglerfish  uses a modified dorsal spine as a fishing rod with a  bioluminescent   lure  to attract and capture prey. [ 1 ]


A  camouflaged   predator :  snow leopard  in  Ladakh . The distinction between aggressive mimicry and predator camouflage depends on the signal given to the prey, not easily determined.


Defensive  Batesian mimics , like this bumblebee-mimicking hoverfly, are the antithesis of aggressive mimics.


Aggressive mimicry compared to a defensive form,  Batesian mimicry . The mechanism is often called " Wolf in sheep's clothing ". The model for an aggressive mimic can be a harmless species, in which case the 3 roles are disjunct, or the model can be the prey itself, in which case the arrangement is bipolar. [ 9 ]


The  alligator snapping turtle  uses its  tongue  to lure fish.


Argiope argentata  and its web


The bright leaves of the  Venus flytrap  ( Dionaea muscipula ) attract insects in the same way as flowers.


Brood parasitism : four clutches of  reed warbler  eggs, each containing one (larger)  cuckoo  egg


The zone-tailed hawk resembles the harmless  turkey vulture  in flight, but attacks other species.


Two bluestreak cleaner wrasse cleaning a  potato grouper ,  Epinephelus tukula


Wolf in Sheep's Clothing  by  Józef Mehoffer , 1903. Detail of album cover


A comparison between  Cepaea hortensis  (left) and  Caucasotachea vindobonensis  (right)


Cepaea nemoralis , showing colour and banding polymorphisms


Proportion of  C. nemoralis  shells that are yellow


Song thrush anvil with broken  Cepaea  shells


Seen here is adaptive radiation of finch A ( Geospiza magnirostris ) into three other species of finches found on the Galapagos Islands. Due to the absence of other species of birds, the finches adapted to new niches. The finches' beaks and bodies changed allowing them to eat certain types of foods such as nuts, fruits, and insects.  Geospiza magnirostris Geospiza parvula Certhidea olivacea Geospiza fortis


Four of Darwin's finches, clockwise (from top left):   Geospiza magnirostris ,  Geospiza fortis ,  Certhidea fusca ,  Camarhynchus parvulus


Here the relation between genotype and phenotype is illustrated, using a  Punnett square , for the character of petal colour in a  pea plant . The letters B and b represent alleles for colour and the pictures show the resultant flowers. The diagram shows the cross between two heterozygous parents where B represents the dominant allele (purple) and b represents the recessive allele (white).


An example of a pedigree for an autosomal dominant condition


An example of a pedigree for an autosomal recessive condition


A female (left) and a male (right)  mallard  ( A. platyrhynchos ). Like many other species of birds, mallards display striking sexual dimorphism.


Reed warbler  ( Acrocephalus scirpaceus ) feeding a cuckoo chick ( Cuculus canorus )


Drosophila  polytene chromosome


Callimorpha dominula  morpha  typica  with spread wings. The red with black rear wings, revealed in flight, warn of its noxious taste. The front wings are cryptic, covering the rear wings at rest. Here the moth is resting but alert, and has jinked the front wings forward to reveal the warning flash.


Cepaea nemoralis , dark yellow shell with single mid band.


Two active  Cepaea  snails


Dissection of thrum and pin flowers of  Primula vulgaris


Many insects including  hoverflies  (C, D, E) and the  wasp beetle  (F) are  Batesian mimics  of stinging  wasps  (A, B), which are  Müllerian mimics  of each other.


Batesian vs Müllerian mimicry: the former is  deceptive , the latter  honest .


Macroxiphus , a harmless bush cricket, mimics a well-defended  ant .


Comparison of Batesian and Müllerian mimicry, illustrated with a  hoverfly , a  wasp  and a  bee


Some  Passiflora  flower species use Gilbertian mimicry, defending against being eaten by larvae of  Heliconius  butterflies with leaf  stipules  (not shown) that resemble the butterfly's eggs. [ 2 ] [ 19 ]


Eyespots  of  foureye butterflyfish  ( Chaetodon capistratus ) mimic its own eyes, deflecting attacks from the vulnerable head.


Two  bluestreak cleaner wrasse  cleaning a  potato grouper ,  Epinephelus tukula


Dasyscolia ciliata , a scoliid wasp,  attempting to copulate  with a flower of the orchid  Ophrys speculum


Rye  is a secondary crop, originally being a mimetic weed of  wheat .


The climber  Boquila trifoliata  varies its leaf shape to resemble the plant it is climbing on, perhaps reducing its conspicuousness to herbivores. [ 1 ]


Carrion flowers attract flies and other carrion-feeding insects by their smell. [ 12 ]   Orbea variegata  illustrated.


Bee orchid  flower resembles a female bee closely enough to attract males in search of a mate


The  shells  of individuals within the  bivalve   mollusk  species  Donax variabilis  show diverse   coloration  and   patterning  in their phenotypes.


Here the relation between  genotype  and phenotype is illustrated, using a  Punnett square , for the character of petal color in pea plants. The letters B and b represent  genes  for color, and the pictures show the resultant phenotypes. This shows how multiple genotypes (BB and Bb) may yield the same phenotype (purple petals).


ABO blood groups determined through a Punnett square and displaying phenotypes and genotypes


Exploring relationships among phenotype, genotype and environment at different levels [ 16 ]


Biston betularia  morpha  typica , the standard light-colored peppered moth


B.betularia  morpha  carbonaria , the melanic form, illustrating discontinuous variation


An organism's phenotype is determined by the sum of its genetic material along with the influence of its environment. This is mediated by a range of biological mechanisms: either the direct activities of gene products or their downstream effects. [ 21 ]


The patchy colors of a tortoiseshell cat are the result of different levels of expression of pigmentation genes in different areas of the skin.


Callimorpha dominula  morpha  typica  with spread wings: the moth manifests in two homozygous morphs and one heterozygous morph.


Adult bagworm moths ( Tinea ephemeraeformis ) mating


The  Heliconius  butterflies from the tropics of the Western Hemisphere are the classical model for  Müllerian mimicry .


Biston betularia  caterpillars on birch (left) and willow (right), demonstrating a color polyphenism. [ 1 ]


Polyphenism in  termites      A : Primary king       B : Primary queen       C : Secondary queen       D : Tertiary queen       E : Soldiers       F : Worker


Insect castes: Replete and worker honeypot ants  Myrmecocystus mimicus


Mouth polyphenism in the nematode  Pristionchus pacificus      A : bacterivorous "stenostomatous" morph       B : predatory "eurystomatous" morph


Third stage  dauer larva  (resting stage) of  Phasmarhabditis hermaphrodita


Mandarin ducks , male (left) and female (right), illustrating the dramatic difference in plumage between sexes, a manifestation of sexual dimorphism


The  peacock , on the right, is courting the  peahen , on the left.


Male (bottom) and female  mallards . The male mallard has an unmistakable bottle-green head when his  breeding plumage  is present.


Orgyia antiqua  male (left) and female (right)


Colias dimera  mating. The male is a brighter yellow than the female.


Female (left) and male (right)  Argiope appensa , displaying typical sexual differences in spiders, with dramatically smaller males


Hammock Spiders (Pityohyphantes sp.) courting. Female left and male right.


Mississippi map turtles  ( Graptemys pseudogeographica kohni ) adult female (left) and adult male (right)


Female (left) and male (right)  golden-shouldered parrot , showing that the male is much more colorful than the female


The  eclectus parrot  is an example of a bird where the female (right) is more colorful than the male (left).


Skeletons of female (left) and Male (right) black-casqued hornbills ( Ceratogymna atrata ). The difference between the sexes is apparent in the casque on the top of their bill. This pair is on display at the  Museum of Osteology .


Male and female  northern elephant seal , the male being larger with a big  proboscis


Pioneer plaque


Male pelvis


Female pelvis


Female  triplewart seadevil , an anglerfish, with male attached near vent (arrow)


Sexual dimorphism in  Cambrian   trilobites [ 145 ]


Male (left), offspring (center), and female (right)  Sumatran orangutans


Hans Eysenck


Cloninger's biological dimensions of personality


Dopamine and Serotonin pathways


The size of a tomato is one example of a complex trait.


A manhattan plot showing genome-association with microcirculation.


Autosomal dominant and autosomal recessive inheritance, the two most common  Mendelian inheritance  patterns. An  autosome  is any chromosome other than a  sex chromosome .


Inheritance of dwarfing in maize. Demonstrating the heights of plants from the two parent variations and their F1 heterozygous hybrid (centre)


Monohybrid cross between homozygote dominant (GG) and homozygote recessive (gg), always resulting in heterozygote genotype (Gg) and the phenotype associated with the dominant allele, in this case capital G.


Monohybrid cross between heterozygotes (Gg), resulting in genptypical ratio 1:2:1 (GG:Gg:gg) and phenotypical ratio 3:1 (G:g).


Dihybrid cross between homozygote dominant (GGRR) and homozygote recessive (ggrr) always resulting in heterozygotes (GgRr)  with phenotype associated with the dominant alleles G and R.


Dihybrid cross between heterozygotes (GgRr), resulting in the phenotypical ratio 9:3:3:1 (G and R: G and r: g and R: g and r)


This  Punnett square  illustrates incomplete dominance. In this example, the red petal trait associated with the R  allele  recombines with the white petal trait of the r allele. The plant incompletely expresses the dominant trait (R) causing plants with the Rr genotype to express flowers with less red pigment resulting in pink flowers. The colors are not blended together, the dominant trait is just expressed less strongly.


Co-dominance in a  Camellia  cultivar


A and B blood types  in humans show co-dominance, but the O type is recessive to A and B.


This Punnett square shows co-dominance. In this example a white bull (WW) mates with a red cow (RR), and their offspring exhibit co-dominance expressing both white and red hairs.


Ronald Fisher in 1913


Studies of heritability ask questions such as to what extent do genetic factors influence  differences  in height between people. This is not the same as asking to what extent do genetic factors influence height in any one person.


Figure 1. Relationship of phenotypic values to additive and dominance effects using a completely dominant locus.


Figure 2.  Francis Galton 's (1889) data showing the relationship between offspring height (928 individuals) as a function of mean parent height (205 sets of parents).


Figure 3. Twin concordances for seven psychological traits (sample size shown inside bars), with DZ being fraternal and MZ being identical twins.


Figure 4. Strength of selection (S) and response to selection (R) in an artificial selection experiment,  h 2 =R/S.


Gene effects and phenotype values.


Analysis of sexual reproduction.


Population mean across all values of p, for various d effects.


Genetic drift example analysis.


Inbreeding resulting from genetic drift in random fertilization.


Random fertilization compared to cross-fertilization


Spatial fertilization patterns


"Islands" random fertilization


Analysis of allele substitution


Components of genotypic variance using the gene-model effects.


Components of genotypic variance using the allele-substitution effects.


Dispersion and components of the genotypic variance


Development of variance dispersion


Connection between the inbreeding and co-ancestry coefficients.


Illustrative pedigree.


Cross-multiplication rules.


Inbreeding in sibling relationships


Inbreeding from full-sib and half-sib crossing, and from selfing.


Self fertilization inbreeding


Pedigree analysis first cousins


Pedigree analysis second cousins


Inbreeding from several levels of cousin crossing.


Pedigree analysis half cousins


Pedigree analysis: backcrossing


Backcrossing: basic inbreeding levels


Genetic advance and selection pressure repeated


Changes arising from repeated selection


Selection differential and the normal distribution


Reproductive coefficients of determination and inbreeding


Path analysis of sexual reproduction.


Sources of phenotypic correlation.


Aristotle's model  of transmission of movements from parents to child, and of  form  from the father. The model is not fully symmetric. [ 1 ]


Sperms  as preformed humans. Painting of  Nicolaas Hartsoeker  1695


Blending Inheritance


Mendelian inheritance  states characteristics are discrete and are inherited by the parents. This image depicts a  monohybrid cross  and shows 3 generations: P1 generation (1), F1 generation (2), and F2 generation (3). Each organism inherits two alleles, one from each parent, that make up the genotype. The observed characteristic, the phenotype, is determined by the dominant allele in the genotype. In this monohybrid cross the dominant allele encodes for the colour red and the recessive allele encodes for the colour white.


Diagram of  Charles Darwin 's pangenesis theory. Every part of the body emits tiny particles,  gemmules , which migrate to the  gonads  and contribute to the fertilised egg and so to the next generation. The theory implied that changes to the body during an organism's life would be inherited, as proposed in  Lamarckism .


August Weismann 's germ plasm theory. The hereditary material, the germ plasm, is confined to the  gonads . Somatic cells (of the body)  develop afresh  in each generation from the germ plasm.


Thomas Hunt Morgan  discovered  sex linked  inheritance of the white eyed mutation in the fruit fly  Drosophila  in 1910, implying the  gene  was on the  sex chromosome .


Francis Crick's handwritten paper, "On Degenerate Templates and the Adaptor Hypothesis: A Note for the RNA Tie Club," privately circulated to members of the RNA Tie Club January 1955.


A tRNA molecule from yeast. Anticodon (triplet sequence in red) is the mRNA-binding site during protein synthesis.


Role of tRNA as an adaptor molecule during protein synthesis.


Benzer with  Ronald Reagan  in 1986


Walter Sutton  (left) and  Theodor Boveri  (right) independently developed different parts of the chromosome theory of inheritance in 1902.


Esther Lederberg ,  Gunther Stent , Sydney Brenner and  Joshua Lederberg  pictured in 1965


Gene map of the human mitochondrial genome corresponding to the revised Cambridge Reference Sequence. [ 1 ]


Francis Crick's 1958 figure showing various information transfers


Unusual flows of information highlighted in green


In  August Weismann 's  germ plasm  theory, the hereditary material, the germ plasm, is confined to the  gonads . Somatic cells (of the body)  develop afresh  in each generation from the germ plasm. Whatever may happen to those cells does not affect the next generation.


Ronald Fisher in 1912


Karl Pearson


Hugo de Vries in the 1890s


Hugo de Vries at his retirement ( Thérèse Schwartze , 1918)


Delbrück in the early 1940s


Delbrück's workplace in Berlin: Kaiser Wilhelm Institute for Chemistry, now the  Free University of Berlin .


Drawing of a plaque in Buttrick Hall, Vanderbilt University commemorating the work of Max Delbrück. [ 18 ]


The DNA double helix


Sir  Alec Jeffreys , pioneer of DNA profiling. His discovery led to the conviction of  Colin Pitchfork  in 1988. [ 1 ]


Variations of  VNTR  allele lengths in 6 individuals


Restriction Fragment Length Polymorphism


Steps of polymerase chain reaction


Short Tandem Repeat (STR) analysis on a simplified model: First, a DNA sample undergoes  polymerase chain reaction  with  primers  targeting certain STRs (which vary in lengths between individuals and their  alleles ). The resultant fragments are separated by size (such as  electrophoresis ). [ 20 ]


CBP  chemist reads a DNA profile to determine the origin of a commodity.


Ewan Birney developed the Ensembl genome software package, at  Hinxton  in Cambridgeshire, to untangle all of the enormous data from the Human Genome Project, in 2000


DNA studies suggested that the dog most likely arose from a common ancestor with the  grey wolf . [ 2 ]


Griffith  proved the existence of a "transforming principle", which  Avery, MacLeod and McCarty  later showed to be  DNA


The bacterium  Agrobacterium tumefaciens  inserts  T-DNA  into infected plant cells, which is then incorporated into the plants  genome .


Paul Berg  created the first  recombinant DNA  molecules in 1972.


In 1974  Rudolf Jaenisch  created the first  GM animal .


A  laboratory mouse  in which a gene affecting hair growth has been  knocked out  (left), is shown next to a normal lab mouse.


Herbert Boyer  helped found the first genetic engineering company in 1976.


As a child


Inverforth House ,  North End Way  NW3, where Fisher lived from 1896 to 1904. He is commemorated with a  blue plaque .


On graduating from Cambridge University, 1912


The peacock tail in flight, the classic example of a Fisherian runaway


Rothamsted Research


Memorial plaque over his remains, lectern-side aisle of St Peter's Cathedral, Adelaide


Stained glass window (now removed) in the dining hall of  Caius College , in Cambridge, commemorating Ronald Fisher and representing a  Latin square , discussed by him in  The Design of Experiments


Ronald Fisher with his sons


Ronald Fisher as a child


Fisher in his graduation ceremony at Cambridge University


Ronald Fisher in 1913


Unidentified woman sat at desk with computing machine. A framed pencil sketch of Francis Galton hangs on the wall above the desk.


An example of an inheritance chart, found in many publications of the Galton Laboratory.


Two unidentified women in the laboratory. One is seated and appears to be measuring a human skull, the other is standing next to a bench.


Staff of William Bragg's laboratory in 1931:  W. H. Bragg  (sitting, center): physicist A. Lebedev (leftmost), G. Gamow (rightmost)


Gamow's grave in Green Mountain Cemetery, Boulder, Colorado, US


The George Gamow Tower at the  University of Colorado Boulder


Title page of a 1949 copy of "Theory of Atomic Nucleus and Nuclear Energy-Sources"


The peacock plumage is a classic example of the hypothesized  Fisherian runaway .


Male  Drosophila pseudoobscura


Fred Griffith in 1936


Griffith's experiment discovering the "transforming principle" in  Streptococcus pneumoniae (pneumococcal) bacteria.


John Masson Gulland (1933)


6 Alva Street, Edinburgh, Gulland's birthplace


The grave of John Masson Gulland, Grange Cemetery, Edinburgh


Robert W. Holley, on the far left


Kossel's grave in  Heidelberg


Lederberg alongside his wife, esteemed microbiologist and feminist figure, [ 7 ]   Esther Lederberg  and their friends  Gunther Stent  and  Sydney Brenner  in 1965


Lederberg (right) receiving The National Medal of Science from George H. W. Bush.


Impact crater  Lederberg  in Xanthe Terra on Mars


Structural formula of a proposed tetranucleotide, later shown to be incorrect. It was proposed by Phoebus Levene around 1910


Salvador Luria with  Esther Lederberg  at the 1953 Cold Spring Harbor Symposium. In the background are  Aaron Novick , Bruce Stocker, Haig Papazian and Geraldine Lindegren.


A summary of the three postulated methods of DNA synthesis


Diagramatic representation of the key structural features of the DNA double helix. This figure does not depict  B-DNA .


DNA replication . The two base-pair complementary chains of the DNA molecule allow replication of the genetic instructions.


Watson and Crick used many aluminium templates like this one, which is the single base  Adenine  (A), to build a physical model of DNA in 1953.


In a typical  Drosophila  genetics experiment, male and female flies with known  phenotypes  are put in a jar to mate; females must be virgins. Eggs are laid in porridge which the larvae feed on; when the life cycle is complete, the progeny are scored for the inheritance of the trait of interest.


Sex linked inheritance of the white eyed mutation.


Morgan's illustration of  crossing over , from his 1916  A Critique of the Theory of Evolution


First genetic map (Sturtevant, 1913). It shows 6 sex-linked genes.


Thomas Hunt Morgan's  Drosophila melanogaster   genetic linkage  map. This was the first successful  gene mapping  work and provides important evidence for the  chromosome theory of inheritance . The map shows the relative positions of  allelic  characteristics on the second  Drosophila  chromosome. The distance between the genes (map units) is equal to the percentage of  crossing-over  events that occurs between different alleles. [ 20 ]


Genetic map of drosophila, published in  The theory of the gene  1926 edition. [ 23 ]


1931 drawing of Thomas Hunt Morgan


Muller's house in  Bloomington, Indiana


Marshall Nirenberg


The Multi-plater, developed by Leder, helped speed up the process of deciphering the genetic code. [ 6 ]


Genetic Code Chart


Nirenberg (right) and Matthaei at the  National Institutes of Health


One of Nirenberg's laboratory notebooks


Nirenberg (right) and  Matthaei  from 1961


Nirenberg from 1962.


Ochoa with wife Carmen García Cobián, in Sweden, 1959


Severo Ochoa Monument outside the school of medicine of the  Complutense University of Madrid


Mention of  Beadle  and  Tatum's  1958 Nobel prize on the monument at the  American Museum of Natural History  in  New York City .


Palade on a 2016 Romanian stamp


Charles Darwin 's pangenesis theory postulated that every part of the body emits tiny particles called gemmules which migrate to the  gonads  and are transferred to offspring. Gemmules were thought to develop into their associated body parts as offspring matures. The theory implied that changes to the body during an organism's life would be inherited, as proposed in  Lamarckism .


August Weismann 's  germ plasm  theory. The hereditary material, the germ plasm, is confined to the gonads. Somatic cells (of the body) develop afresh in each generation from the germ plasm. The implied  Weismann barrier  between the germ line and the soma prevents Lamarckian inheritance.


Herman Henry William Pauling, Linus Pauling's father,  c.  1900


Pauling's graduation photo from  Oregon State University , 1922


Linus Pauling with an inset of his Nobel Prize in 1955


Pauling in 1941


An alpha helix in ultra-high-resolution electron density contours, with O atoms in red, N atoms in blue, and hydrogen bonds as green dotted lines (PDB file 2NRL, 17–32)


Pauling in 1948


Pauling in 1962


Beckman D2 Oxygen Analyzer, ca. 1950


Beckman Model 735 Dissolved O 2  Analyzer, later model based on Pauling's design, 1968


Beckman Model D Oxygen Meter, based on Pauling's design, with infant incubator, 1959


Denial letter from  Ruth B. Shipley , Chief Passport Division, Department of State to Linus Pauling on February 14, 1952


Pauling's beret on display at the  Nobel Prize Museum


Pauling's book,  How to Live Longer and Feel Better , advocated very high intake of  Vitamin C . [ 133 ]


The Pauling children at a gathering in celebration of the 1954 Nobel Prizes in Stockholm, Sweden. Seated from left: Linus Pauling, Jr., Peter Pauling and Linda Pauling. Standing from left: an unidentified person, and Crellin Pauling


Photo 51 , showing X-ray diffraction pattern of DNA


Cartoon explanation of how  Photo 51  captured the double helix structure of DNA.


Nicole Kidman  starred as  Rosalind Franklin


Stephen Campbell Moore  starred as  Maurice Wilkins


A Punnett square


Discussions in 1896 at Newnham College.  Marion Greenwood  is second from left and Edith Saunders is at right


Glucos 6-phosphate dehydrogenase.


Repeating tetranucleotide unit


In  Griffith's experiment , mice are injected with dead bacteria of one strain and live bacteria of another, and develop an infection of the dead strain's type.


Hershey–Chase experiment  proves that  phage  genetic material is  DNA .


Meselson–Stahl experiment  demonstrates DNA is  semiconservatively replicated .


In 1972, the first gene was sequenced: the gene for  bacteriophage MS2  coat protein (3 chains in different colours).


Display of  VNTR  allele lengths on a chromatogram, a technology used in  DNA fingerprinting


Francis Collins announces the successful completion of the  Human Genome Project  in 2003


7 James Street. Now a  Vape shop , previously used as a  bookmaker 's.


The 1988 police  E-FIT  of the prime suspect, a white male, seen outside 7 James Street.


Phylogenetic tree based on Woese et al. rRNA analysis. The vertical line at bottom represents the  last universal common ancestor  (LUCA). [ 4 ]


Visualization of a fitness landscape. The X and Y axes represent continuous phenotypic traits, and the height at each point represents the corresponding organism's fitness. The arrows represent various mutational paths that the population could follow while evolving on the fitness landscape.


Diagram of a replicated and condensed  metaphase  eukaryotic chromosome:  Chromatid Centromere Short arm Long arm


Organization of DNA in a eukaryotic cell


The major structures in DNA compaction:  DNA , the  nucleosome , the 10 nm "beads-on-a-string" fibre, the 30 nm fibre and the  metaphase  chromosome


Heterochromatin vs. euchromatin


Human chromosomes during  metaphase


Stages of early mitosis in a vertebrate cell with micrographs of chromatids


Karyogram of a human male


Schematic  karyogram  of a human, with annotated  bands and sub-bands . It is a graphical representation of the idealized human  diploid  karyotype. It shows dark and white regions on  G banding . Each row is vertically aligned at  centromere  level. It shows 22  homologous chromosomes , both the female (XX) and male (XY) versions of the  sex chromosome  (bottom right), as well as the  mitochondrial genome  (at bottom left).  Further information:  Karyotype


In Down syndrome, there are three copies of chromosome 21.


The 23 human  chromosome territories  during  prometaphase  in  fibroblast  cells


Image of  chicken  chromosomes featuring the many microchromosomes (appearing as dots). The arrows indicate a stained  gene locus  on homologous macrochromosomes.


Autosomal dominant inheritance


An illustration of the inheritance pattern and phenotypic effects of an autosomal recessive gene.


Siberian roe deer  metaphase spread with B chromosomes


A balancer chromosome contains large inversions ([B,C,D] and [G]).  Normal genetic recombination ( blue X ) is suppressed ( red X ) at these sites.


A bivalent


Predicted tertiary structure of c7orf26 with leucine zipper elements highlighted in red, and dileucine components highlighted in green.


Location of c7orf26 on chromosome 7


Diagram depicting the expression of c7orf26 in tissues throughout the body.


Phylogenetic Tree of nearest orthologs of c7orf26


Evolution of the C12orf40 gene (and its more conserved sub-region of the first 4 exons) across several taxa. Information available from NCBI BLAST software.


NCBI GEO Expression Profile for C18orf63


Amino acid composition of the average protein (left) and Amino acid composition of C18orf63 (right)


Partial 3D structure for C18orf63


Motifs and Domains for C18orf63


Rate of evolution for C18orf63 when compared to betaglobin, fibrinogen alpha, and cytochrome c


In this diagram of a duplicated chromosome, (2) identifies the centromere—the region that joins the two  sister chromatids , or each half of the chromosome. In prophase of mitosis, specialized regions on centromeres called  kinetochores  attach chromosomes to spindle fibers.


Classifications of Chromosomes       I   Telocentric   Centromere placement very close to the top, p arms barely visible if visible at all.      II   Acrocentric   q arms are still much longer than the p arms, but the p arms are longer than those in telocentric.      III   Submetacentric   p and q arms are very close in length but not equal.      IV   Metacentric   p and q arms are equal in length.      A : Short arm (p arm) B : Centromere C : Long arm (q arm) D : Sister Chromatids


Human  karyogram , with each row vertically aligned at centromere level, and with annotated  bands and sub-bands . It is a graphical representation of the idealized human  diploid  karyotype. It shows dark and white regions on  G banding . It shows both the female (XX) and male (XY) versions of the  sex chromosome .  Further information:  Karyotype


The 154 kb chloroplast DNA map of a model flowering plant ( Arabidopsis thaliana : Brassicaceae) showing genes and inverted repeats.


Chloroplast DNA replication via multiple D loop mechanisms. Adapted from Krishnan NM, Rao BJ's paper "A comparative approach to elucidate chloroplast genome replication."


Over time, base changes in the DNA sequence can arise from deamination mutations. When adenine is deaminated, it becomes hypoxanthine, which can pair with cytosine. During replication, the cytosine will pair with guanine, causing an A → G base change.


In the diagram, (1) refers to a chromatid: 1-half of two identical threadlike strands of a replicated  chromosome . During cell division, the identical copies (called a " sister chromatid pair ") are joined at the region called the  centromere  (2). Once the paired sister chromatids have separated from one another (in the  anaphase  of   mitosis ) each is known as a daughter chromosome. The short arm of the right chromatid (3), and the long arm of the right chromatid (4), are also marked.


Schematic  karyogram  of the human chromosomes, showing their usual state in the G 0  and G 1  phase of the cell cycle. At top center it also shows the chromosome 3 pair in  metaphase  (annotated as "Meta."), which takes place after having undergone  DNA synthesis  which occurs in the  S phase  (annotated as S) of the cell cycle. During metaphase, each chromosome is duplicated into  sister chromatids . Further information:  Karyotype


Condensation and resolution of human sister chromatids in early mitosis


A . "Budding"  nucleus  with nucleoplasmic bridge (arrow), a chromatin bridge after mitosis.


A.   Microtubules  localized at a chromatin bridge. These polymers are stained with anti-tubulin antibody and viewed using  fluorescence microscopy .  B.  Merged images of two daughter cells connected by a chromatin bridge. The fluorescence techniques of  indirect immunofluorescence  and DAPI staining were utilized.  C.  The same cells visualized using DAPI staining.


A  chromatin  bridge, visualized using DAPI staining.


Polytene chromosome of Drosophila. (b) Displays the chromomeric and interchromomeric bands of the chromosome.


A clay model showing why heterozygous inversion loops are visible in  polytene chromosome  preparations


An inversion loop in the A arm of a chromosome from an  Axarus  species midge


Three chromosomal abnormalities with ISCN nomenclature, with increasing complexity:  (A)  A tumour karyotype in a male with loss of the Y chromosome,  (B)  Prader–Willi Syndrome i.e. deletion in the 15q11-q12 region and  (C)  an arbitrary karyotype that involves a variety of autosomal and allosomal abnormalities including inversions (abbreviated as  inv ). [ 19 ]


Human  karyotype  with annotated bands and sub-bands as used for the nomenclature of chromosome abnormalities. It shows dark and white regions as seen on  G banding . Each row is vertically aligned at  centromere  level. It shows 22  homologous   autosomal  chromosome pairs as well as both the female (XX) and male (XY) versions of the two  sex chromosomes .  Further information:  Karyotype


Chromosome conformation capture technologies


Heat map and circular plot visualization of Hi-C data. a. Hi-C interactions among all chromosomes from G401 human kidney cells, as plotted by the my5C software. [ 60 ]  b. Heat map visualization illustrating the bipartite structure of the mouse X chromosome, as plotted by Hi-Browse. [ 61 ]  c. Heat map visualization of a 3 Mbp locus (chr4:18000000-21000000), produced by Juicebox, using in-situ Hi-C data from the GM12878 cell line. [ 4 ]  d. Circular plot of the bipartite mouse X chromosome, generated by the Epigenome Browser. [ 62 ]  Image from  [ 63 ]


A typical chromosome with its structures. Often, the centromere has a three layered covering known as Kinetochore.


Diagram of a duplicated and condensed ( metaphase ) eukaryotic chromosome. (1)  Chromatid  – one of the two identical parts of the chromosome after  S phase . (2)  Centromere  – the point where the two chromatids touch, and where the microtubules attach. (3) Short arm ( p ). (4) Long arm ( q ).


Immunodetection of a  chromosome  showing  DNA  (blue) and two scaffold proteins:  SMC2  (red) and  topoisomerase IIα  (green) [ 1 ]


Mitosis divides the  chromosomes  in a  cell nucleus .


A diagram of the meiotic phases


A current model of meiotic recombination, initiated by a double-strand break or gap, followed by pairing with an homologous chromosome and strand invasion to initiate the recombinational repair process. Repair of the gap can lead to crossover (CO) or non-crossover (NCO) of the flanking regions. CO recombination is thought to occur by the Double Holliday Junction (DHJ) model, illustrated on the right, above. NCO recombinants are thought to occur primarily by the Synthesis Dependent Strand Annealing (SDSA) model, illustrated on the left, above. Most recombination events appear to be the SDSA type.


Chromothripsis: Single catastrophic event in a cell's history


Non homologous end joining and Microhomology mediated end joining


Schematic of Micronucleus model of chromothripsis


A circular chromosome, showing DNA replication proceeding bidirectionally, with two replication forks generated at the "origin". Each half of the chromosome replicated by one replication fork is called a "replichore". (Graphic computer art by Daniel Yuen)


Bidirectional replication in a circular chromosome.


oriC  motifs in bacteria


Most circular bacterial chromosomes are replicated bidirectionally, starting at one point of origin and replicating in two directions away from the origin. This results in semiconservative replication, in which each new identical DNA molecule contains one template strand from the original molecule, shown as the solid lines, and one new strand, shown as the dotted lines.


Human  karyotype  with annotated  bands and sub-bands  as used for the nomenclature of  chromosome abnormalities . It shows 22  homologous   autosomal  chromosome pairs, both the female (XX) and male (XY) versions of the two  sex chromosomes , as well as the  mitochondrial genome  (at bottom left).  Further information:  Karyotype


After a paracentric inversion, separation of the inverted chromosomes in anaphase I result in the formation of dicentric and acentric fragments. The dicentric fragments  become broken, deleted products. The acentric fragments are simply lost.


The presence of "tailed" nuclei ( B ) in irradiated cells are considered biomarkers of dicentric chromosome formation.


Schematic  karyogram  of a human as seen on G banding, with annotated  bands and sub-bands . It is a graphical representation of the idealized human  diploid  karyotype. Each row is vertically aligned at  centromere  level. It shows 22  homologous   autosomal  chromosome pairs, both the female (XX) and male (XY) versions of the two  sex chromosomes , as well as the  mitochondrial genome  (at bottom left).  Further information:  Karyotype


Schematic of a Holliday junction showing the  base sequence  and  secondary structure  but not the  tertiary structure . The sequence shown is only one of many possibilities. This is an immobile Holliday junction because the sequences are not symmetrical.


Schematic diagrams of the three base-stacking  conformational isomers  of the Holliday junction. The two stacked conformers differ in which sets of two arms are bound by  coaxial stacking : at left, the stacks are red–blue and cyan–magenta, while at right the stacks are red–cyan and blue–magenta. The bases nearest to the junction point determine which stacked isomer dominates.


The two pathways for  homologous recombination  in  eukaryotes , showing the formation and resolution of Holliday junctions


This double-crossover (DX)  supramolecular complex  contains two Holliday junctions between the two  double-helical  domains, on the top and the bottom in this image. This tile is capable of forming two-dimensional arrays. [ 21 ]


Diagrams of a  tensegrity  triangle complex containing three Holliday junctions, both in isolation (a) and as part of a crystal (b, c). In addition to the two-dimensional array shown, this structure is capable of forming three-dimensional crystals. [ 24 ]


As this  karyotype  displays a  diploid  human cell contains 22 pairs of homologous chromosomes and 2 sex chromosomes. The cell has two sets of each chromosome; one of the pair is derived from the mother and the other from the father. The maternal and paternal chromosomes in a homologous pair have the same  genes  at the same  locus , but possibly different  alleles .  Further information:  Karyotype


During the process of meiosis, homologous chromosomes can recombine and produce new combinations of genes in the daughter cells.


Sorting of homologous chromosomes during meiosis.


1. Meiosis I 2. Meiosis II 3. Fertilization 4. Zygote Nondisjunction is when chromosomes fail to separate normally resulting in a gain or loss of chromosomes. In the left image the blue arrow indicates nondisjunction taking place during meiosis II. In the right image the green arrow is indicating nondisjunction taking place during meiosis I.


Diagram of the general process for double-stranded break repair as well as synthesis-dependent strand annealing.


Dynamic chromosome pairing. The term “pairing” describes the spatial juxtaposition of entire homologous chromosomes, allelic sequences, and/or homologous sequences at non-allelic locations. (A, B) Homologous chromosomes can exist as paired throughout their entire length and the relative activities of pairing and anti-pairing factors determine the degree of global chromosome pairing. (C) Local pairing and anti-pairing factors can affect pairing status of specific genes or chromosomal regions. Local “pairing centers” can nucleate global pairing, but it is unclear whether factors regulating local pairing are different from global pairing factors. (D–F) In some cases, centromeres or telomeres from homologs can pair or cluster with non-homologous chromosomes, while there is no pairing along chromosome arms


Isochromosome in which the arms are mirror copies of each other.


Isochromosome formation through the misdivision of the centromere.  Monocentric  isochromosomes contain arms that are mirror images of each other.


Lampbrush chromosome


Parts of a typical chromosome: (1)  Chromatid (2)  Centromere (3) Short (p) arm (4) Long (q) arm


Cytogenetic banding  nomenclature


Example of cytogenetic bands


Comparative telomeric array organization within and among diverse chicken genotypes illustrates intra-genomic, inter-individual, and inter-genotype variation


Chromosomal locations of mega-telomeres in an inbred chicken line: GGA (chromosome) 9 and W


Slot blot method of analysis can be utilized to determine the total amount of telomeric sequence per genome (inclusive of interstitial and terminal arrays)


Duplicated chromosome. (2) identifies the Monocentric centromere—the region that joins the two  sister chromatids , or each half of the chromosome. In prophase of mitosis, specialized regions on centromeres called  kinetochores  attach chromosomes to spindle fibers.


A summary of the types of breakages and subsequent rearrangements that lead to the formation of neocentromeres.


Acanthocytosis in a patient with  abetalipoproteinemia


Transcript Variants of C20orf111


Expression of Perit1 in cancerous cells according to NCBI Geo Profiles. [ 22 ]


MSA of the orthologs of OSER1 protein


C20orf111 protein schematic showing predicted secondary structure and post-translational modifications.


Polytene chromosomes in a  Chironomus  salivary gland cell


Polytene chromosome


The hierarchical folding model of chromosome condensation


Formation of a ring chromosome


Schematic  karyogram  of a human. Each row is vertically aligned at  centromere  level. The top of chromosomes 13, 14, 15, 21, & 22 are satellites, with a  secondary constriction  between the satellite and the centromere. Further information:  Karyotype


Human male XY chromosomes after  G-banding


Schematic  karyogram  of a human, showing the sex chromosomes in green box at bottom right. The X chromosome is part of  chromosome group  C, and the Y chromosome is part of group G.  Bands and sub-bands  are annotated to the right of each chromosome (or chromosome pair), and the gene for the  sex-determining region Y protein  is located at Yp11.2. Further information:  Karyogram


Human  chromosomes  (grey) capped by telomeres (white)


Lagging strand during DNA replication


Shelterin co-ordinates the T-loop formation of telomeres.


Synthesis of chromosome ends by telomerase


The average cell will divide between 50 and 70 times before cell death. As the cell divides the telomeres on the end of the chromosome get smaller. The  Hayflick limit  is the theoretical limit to the number of times a cell may divide until the telomere becomes so short that division is inhibited and the cell enters senescence.


Vaginal expander ZSI 200 NS


ZSI 200 NS vaginal expander stretching the female vagina


The number of possible ancestors on the X chromosome inheritance line at a given ancestral generation follows the Fibonacci sequence. (After Hutchison, L. "Growing the Family Tree: The Power of DNA in Reconstructing Family Relationships". [ 7 ] )


Nucleus of a female amniotic fluid cell. Top: Both X-chromosome territories are detected by  FISH . Shown is a single optical section made with a  confocal microscope . Bottom: Same nucleus stained with  DAPI  and recorded with a  CCD camera . The Barr body is indicated by the arrow, it identifies the inactive X (Xi).


A geneticist explaining gene sequencing.


Two adenovirus particles surrounded by numerous, smaller adeno-associated viruses (negative-staining electron microscopy, magnification approximately 200,000×)


AAV2 capsid, shown as a  ribbon diagram , with the back half hidden for clarity.  One fivefold symmetry axis is shown center.


Gene therapy using an  AAV  vector. A new gene is inserted into a cell using the AAV protein shell. Once inside the nucleus, the new gene makes functional  protein  to treat a disease.


Ames test procedure


Fluctuation method:  96-well plate


Fluctuation method: 384-well plate


AIMS can be used to identify five European "clusters"


Former Ancestry.com headquarters in  Provo, Utah


Steps of IVF Treatment


Intracytoplasmic sperm injection (ICSI)


Number of assisted reproductive technology cycles in Europe between 1997 and 2014 [ 35 ] [ 36 ]


Conditions of assisted reproductive technology in different European countries: [ 35 ] [ 38 ]      ART authorized for lesbian couples      ART authorized for single women      ART authorized for single women and lesbian couples      ART prohibited for single women and lesbian couples


A human  mesenchymal stem cell  expressing microtubule associated protein fusion to  Green fluorescent protein  (green) and histone 2b fusion to tagRFP (red) via BacMam gene delivery technology.


Blood samples are collected from a newborn baby in  Sweden  for the national PKU registry biobank.


Schematic of a monolamellar liposome. The hydrophilic head of the phospholipid faces outwards while the hydrophobic tail faces inwards, forming a lipid bilayer.


Mechanisms of CME, CavME, and macropinocytosis. These endocytic pathways are all common in the delivery of nucleic acids from lamellar cationic liposomes.


Dwarfism due to the sex-linked recessive gene  dw . Comparative size of two full-sib roosters. Left: Normal sibling (genotype  Dw/dw ). Right: Dwarf sibling (genotype  dw/dw ).


A 1930s exhibit by the  Eugenics Society . Some of the signs read "Healthy and Unhealthy Families", " Heredity  as the Basis of Efficiency" and "Marry Wisely".


Lester Frank Ward  wrote the early paper: "Eugenics, Euthenics and Eudemics", making yet further distinctions. [ 15 ]


Giuseppe Diotti's  The selection of the infant Spartans  (1840)


Francis Galton  (1822–1911) was a British polymath who coined the term "eugenics".


Marie Stopes  in her laboratory, 1904


Schloss Hartheim , a former center for Nazi Germany's  Aktion T4  campaign


In the decades after  World War II , the term "eugenics" had taken on a negative connotation and as a result, the use of it became increasingly unpopular within the scientific community. Many organizations and journals that had their origins in the eugenics movement began to distance themselves from the philosophy which spawned them, as when  Eugenics Quarterly  was renamed  Social Biology  in 1969.


Logo from the  Second International Eugenics Conference , 1921. The bottom text reads: "Like A Tree, Eugenics Draws Its Materials From Many Sources And Organizes Them Into An Harmonious Entity" (such sources, i.e. roots, purportedly including e.g.  genetics ,  physiology ,  mental testing ,  anthropology ,  statistics ,  medicine ,  politics  and  sociology ). [ 147 ]


Julian Savulescu , a bioethicist and former PhD student of  Peter Singer


Incomplete  pedigree chart  of  House Atreides  from which one half of the  Kwisatz Haderach  had been strategically bred


In the movie, " Gattaca " also refers to the  futuristic  building complex that hosts the astronauts for an ongoing  space colonization  program.


Family history of haemophilia in the family of Queen Victoria


FamilyTreeDNA uses NovaSeq  sequencing system by Illumina Inc.  for its services. (System in different facility pictured.)


Diagram showing steps involved in  intracytoplasmic sperm injection . Insemination fraud could occur in the third step.


Diagram of  injection  of a  spermatozoon  into a human  egg cell


State penalizes some form of fertility fraud      An active bill is pending


Bacterial transformation involves moving a gene from one bacteria to another. It is integrated into the recipients plasmid. and can then be expressed by the new host.


Electroporators can be used to make the cell membrane permeable to DNA


A gene gun uses  biolistics  to insert DNA into cells


A. tumefaciens  attaching itself to a carrot cell


Foreign DNA being transduced into the host cell through an adenovirus vector.


gene therapy


A duplex of crRNA and  tracrRNA  acts as guide RNA to introduce a specifically located gene modification based on the RNA 5' upstream of the crRNA. Cas9 binds the tracrRNA and needs a DNA binding sequence (5'NGG3'), which is called protospacer adjacent motif (PAM). After binding, Cas9 introduces a DNA double strand break, which is then followed by gene modification via homologous recombination (HDR) or non-homologous end joining (NHEJ).


Gene therapy using an  adenovirus  vector. In some cases, the adenovirus will insert the new gene into a cell. If the treatment is successful, the new gene will make a functional  protein  to treat a disease.


Suicide gene therapy graphic used to treat cancer


A genetic counsellor discussing a  pedigree  with a client


Knowing which family members have inherited  genetic variants  is key to assessing individual and reproductive risk in genetic counselling.


A baby may be examined by a clinical geneticist as part of pediatric genetic counselling


A map showing locations and numbers of practicing genetic counsellors


Genetic counselling is routinely performed via telehealth


Average population fitness ( W ) against number of generations ( t ) of maintenance with population size N=10 when, in the original population, each gamete carried on the average one rare recessive lethal. Evolution of  W  expected only from inbreeding (red line) or from inbreeding and purging (blue line).


Giuseppe Diotti's  The selection of the infant Spartans  (1840)


Morel  claimed that environmental factors such as  drugs or alcohol  would revert one's  offspring  to an evolutionarily more primitive stage. [ 23 ]


Sir  Francis Galton  initially developed the ideas of eugenics using social statistics.


Galton's view of the British class structure was the basis and emphasis of the eugenics movement in Britain.


A  pedigree chart  from  The Kallikak Family  meant to show how one illicit tryst could lead to an entire generation of  imbeciles .


Anthropometry  demonstrated in an exhibit from a 1921 eugenics conference.


Three generations of  racial whitening  in a family of  Australian Aborigines . From right to left: a  half-caste  grandmother with her  quadroon  daughter and  octoroon  grandson. Image from a 1947 book by  eugenicist   A. O. Neville .


Portrait "Redenção de Can" (Ham's Redemption), (1895), by  Galician  painter  Modesto Brocos ,  illustrating the process of racial whitening ( branqueamento ) through  miscegenation  in  Brazil . The painting shows a Brazilian family: The grandmother is black, the mother is mulatto, the father is white, and the baby is white. Note the grandmother gesturing "thank god my grandson is white". [ 109 ]


Hartheim Euthanasia Centre  in 2005


Philipp Bouhler , Head of the  Aktion T4  programme


Cover of the 1918 British Bluebook, originally available "At any bookstore or through H. M. Stationery Office [His Majesty's Stationery Office]", until 1926, when it was removed from the public and destroyed. [ 128 ] [ 129 ]


In the decades after  World War II , eugenics became increasingly unpopular within academic science. Many organizations and journals that had their origins in the eugenics movement began to distance themselves from the philosophy, as when  Eugenics Quarterly  became  Social Biology  in 1969.


Structure of a virion of HIV, a type of lentivirus. A membrane with protruding glycoproteins surrounds a capsid containing enzymes and the viral RNA genome.


Schematic of a monolamellar liposome.


The first hybrid between the mare and the quagga


The mare with the subsequent foal


Minicircle preparation from a parental plasmid. The parental plasmid contains two recombinase target sites (black half arrows). Recombination between these sites generates the desired minicircle (bottom right) together with the  miniplasmid (bottom left). The hook on the red minicircle-insert stands for a scaffold-matrix attachment region (  S/MAR-Element ), which allows for autonomous replication in the recipient cell.


Schematic illustration of nanoemulsion structure, including the biphasic systems (O/W or W/O), in which an appropriate volume of the internal oil phase is disseminated in the bulk aqueous solution or vice versa; and the multiple systems (W/O/W or O/W/O), within a single system, the inner water phase is dispersed in an oil phase, which is then dispersed in a bulk aqueous phase or vice versa. [ 2 ]


The dual-light particle analyzer


Overall goals of oncogenomics


Current technologies being used in Oncogenomics.


The procedure to generate transgenic insects by germ-line transformation.


The procedure of insect transformation via transgenic symbionts.


Autosomal recessive pattern, showing how two unaffected carriers can have a child with the disease.


When a population is in  Hardy–Weinberg equilibrium , the proportions of each  genotype  are directly determined by  allele frequency  as shown in this chart.  Mate choice  is one of the  ways to move a population out of equilibrium , allowing genotype frequency to change even if the underlying allele frequencies remain constant.


Triple Stranded DNA: TFOs bind in a similar fashion to the double stranded DNA as a  triplex helix configuration .


Cartoon representation of a synthetic polyamide to DNA sequence recognition. The DNA sequence 5'-GTAC-3' is recognized by the amino acid pairs Py/Im, Py/Hp, Hp/Py, and Im/Py. See [ 8 ] [ 9 ]  for chemical structure


Synthetic polyamide blocking of RNA transcription by binding within the transcribed region


Synthetic polyamide blocking of transcription factors


Synthetic polyamide conjugated to modifying agent


Example of zinc-finger motifs


Zinc fingers binding a DNA helix


Epigenetic mechanisms


Electroporator with square wave and exponential decay waveforms for in vitro, in vivo, adherent cell and 96 well electroporation applications. Manufactured by BTX Harvard Apparatus, Holliston MA USA.


How vectors work to transfer genetic material


Heterochromatin vs. euchromatin


Diagram showing an adapter within a plasmid


This model illustrates polygenic additive effects on phenotype


Visualization of the decreasing variation of additive effects to mean fitness over generations.


Method for creating a chromosome jumping library.


This is a rendering of cis-acting replication element inspired by an image of common cre structure found in Coronavirus from a review paper by Sola et al., 2015 [ 1 ]


The evolutionary divergence of the CYP superfamily collected in 1990, CYP11,  CYP10  and  CYP27  are in the same branch, [ 1 ]  which is now called  Mitochondrial clan  CYP s . [ 2 ]


The evolutionary divergence of the CYP superfamily collected in 1990, CYP55 is in the branch of  prokaryotic  CYPs


The evolutionary divergence of the CYP superfamily collected in 1990, CYP105A, B and C is in the branch of  prokaryotic  CYPs [ 1 ]


The evolutionary divergence of the CYP superfamily collected in 1990, CYP107 is the seventh  prokaryotic  CYP family identified [ 1 ]


Transfer RNA


A de Finetti diagram. The curved line is the expected  Hardy–Weinberg frequency  as a function of  p .


DNA replication . The two base-pair complementary chains of the DNA molecule allow for replication of the genetic instructions.


Equipment  for bioanalytical continuous- elution   gel electrophoresis : electrophoresis chamber,  peristaltic pump , fraction collector, buffer recirculation pump and  UV detector  (in a  refrigerator ),  power supply  and recorder (on a table). [ 1 ]


"Omicum": Building of the Estonian Genome Centre and Institute of Molecular and Cell Biology at the University of Tartu in Tartu, Estonia.


Organization of the eukaryotic nuclear ribosomal DNA tandem repeats.


A simple phylogenetic tree example made from arbitrary data D


Same tree but made from D1, which consists in the first DNA sites from D


A diagram depicting CAR T-cell therapy from the National Cancer Institute (NCI)


Comparison between healthy red blood cells and red blood cells in an individual with sickle cell anemia.


Genetic Information Research Institute logo


Comparison of skeletons of  T  residue of GNA (red) and natural T  nucleotide  in DNA (blue)


Migration of Haplogroup C (Y-DNA)


This animation shows the spread of  anatomically modern humans  throughout Eurasia and Africa during the  Upper Paleolithic  period, by Currat & Excoffier (2004). [ 2 ] 　This corresponds with the spread of Haplogroups C1, among others.


Likely migration route of haplogroup D according to Haber et al. 2019


Migration route of haplogroup D


Projected spatial frequency distribution for haplogroup L4.


Schematic tree of mtDNA haplogroup L4. Ages (in  ka ) indicated are maximum likelihood estimates obtained for the whole-mtDNA genome.


Projected spatial frequency distribution for haplogroup L6.


Schematic tree of mtDNA haplogroup L6 (and L4). Ages (in  ka ) indicated are maximum likelihood estimates obtained for the whole-mtDNA genome.


Map of Haplogroup S mtDNA


HCT116 cells stained for  γ‐H2AX  (green) and  telomeric   DNA  (red)


An example diagram of a MSO microarray that would be used to produce a calibration curve


As proven in the Hollander et al. paper.


Location of the  MT-RNR2  gene on the H strand of the human mitochondrial genome.  MT-RNR2 , or  RRNL , is one of the two mitochondrial ribosomal RNA genes (blue boxes).


Recognition site of  Nla III with a red line indicating the cutting pattern


Example of mutant GFP that glow different colors to paint a picture of a beach


Illustration of typical restriction enzyme cleavage.


Graph of  neighbor-net   phylogenetic network  shows a clear split support (visualised by long parallel edges) for  Acochlidiacea  (in red color). The graph is based on datasets by Jörger et al. (2010) [ 1 ]  and generated by  SplitsTree .


Overview of some chromosomal translocations involved in different cancers, as well as implicated in some other conditions, e.g. schizophrenia, [ 1 ]  with chromosomes arranged in standard  karyogram  order. t(11;14) is seen in center.  Abbreviations:  ALL –  Acute lymphoblastic leukemia   AML –  Acute myeloid leukemia   CML –  Chronic myelogenous leukemia   DFSP –  Dermatofibrosarcoma protuberans


Consensus structure  of TB3Cs2H1


Consensus structure of TB6Cs1H1


Consensus structure of TB6Cs1H3


Consensus structure of TB9Cs1H1


Consensus structure of TB10Cs3H1


Consensus structure of TB11Cs4H3


A rolled tongue


Cloverleaf tongue - 4 times


Trans-acting factors in alternative splicing in mRNA. Alternative splicing is a key mechanism that is involved in gene expression regulation. In the alternative splicing, trans-acting factors such as SR protein, hnRNP and snRNP control this mechanism by acting in trans. SR protein promotes the spliceosome assembly by interacting with snRNP(e.g. U1, U2) and splicing factors(e.g. U2AF65), and it can also antagonize the activity of hnRNP that inhibits splicing.


X hyperactivation in male Drosophila compensates for having a single X chromosome. Before the X is hyperactivated (left panel), the single X chromosome in males results in only half as much overall gene expression as the two X chromosomes in females. After X hyperactivation (right panel), the X chromosome expression is doubled in males, resulting in an equivalent gene dosage to the two X chromosomes in females.


Human chromosome 1


Human chromosome 2. The short arm where the deletion occurs is to the top


DiGeorge syndrome is inherited in an  autosomal dominant  pattern.


Result of FISH analysis using LSI probe (TUPLE 1) from DiGeorge/velocardiofacial syndrome critical region. TUPLE 1 ( HIRA ) probe was labeled in Spectrum Orange and  Arylsulfatase A  (ARSA) in Spectrum Green as control. Absence of the orange signal indicates deletion of the TUPLE 1 locus at 22q11.2.


Brain computer tomography cuts of the person, demonstrating basal ganglia and periventricular calcification [ 44 ]


Rhodeus ocellatus


Erythrura Gouldiae


Mus Domesticus


Drosophila Melanogaster


Aedes aegypti


Birth of a cell with karyotype XXY due to a  nondisjunction  event of one X chromosome from a Y chromosome during  meiosis I  in the male


Birth of a cell with karyotype XXY due to a nondisjunction event of one X chromosome during  meiosis II  in the female


Intracytoplasmic sperm injection


Illustration of a cross section of a septate uterus in  homo sapiens  (modern day humans) reflecting an anomalous extension of the septum, resulting in inflammation and hypomenorrhea due to reduction of the cervical opening.


The stages of Müllerian duct development in the human embryo and its associated outcomes during normal and impaired development.


In the  ABO blood group system , a person with Type A blood displays A-antigens and may have a genotype I A I A  or I A i. A person with Type B blood displays B-antigens and may have the genotype I B I B  or I B i. A person with Type AB blood displays both A- and B-antigens and has the genotype I A I B  and a person with Type O blood, displaying neither antigen, has the genotype ii.


Danube crested newt ( Triturus dobrogicus )


Flowers would converge to a single coloration in a few generations if  inheritance  blended the characteristics of the two parents.


Diagram of  Charles Darwin 's pangenesis theory. Every part of the body emits tiny particles,  gemmules , which migrate to the  gonads  and contribute to the fertilised egg and so to the next generation. The theory implied that changes to the body during an organism's life would be inherited, as proposed in  Lamarckism , and that  inheritance  would be blending.


Blending inheritance leads to the averaging out of every characteristic, which as the engineer  Fleeming Jenkin  pointed out, would make natural selection impossible if blending were the mechanism of inheritance. [ 1 ] [ 5 ] [ 6 ]


A  Punnett square  for one of Mendel's pea plant experiments - self-fertilization of the F1 generation, shows that inheritance is  particulate , not blending.


Example of a complementation test. Two strains of flies are white-eyed because of two different autosomal recessive mutations that interrupt different steps in a single pigment-producing metabolic pathway. Flies from Strain 1 have complementary mutations to flies from Strain 2 because when they are crossed the offspring can complete the full metabolic pathway and thus have red eyes.


Sister chromosomes with recombinant DNA


Dendrogram of multiple clusters


Thomas Hunt Morgan


A. Nucleus, B. Nuclear Profile - Thin slice of Nucleus, C. Loci - Parts of a target gene found within the Nuclear Profile


Displays the communities for a specific loci using centrality


A sample of the 2D dataset that was used for the application of the cosegregation example.


pseudo-code showcasing the implementation of co-segregation in data science.


How adding more NPs to dataset affects cosegregation equation.


Adding loci affects the cosegregation equation in a linear time complexity.


This co-segregation heat map of genetic windows has not been normalized, the pattern is much less clear and the data is not as meaningful compared to the normalized version.


This co-segregation heat map of genetic windows has been normalized, the pattern is much more clear and that data can more easily and accurately be interpreted.


This is a dihybrid cross of two heterozygous parents. The traits observed in this cross are the same traits that Mendel was observing for his experiments. This cross results in the expected phenotypic ratio of 9:3:3:1.


An example of epistasis is the interaction between hair colour and baldness. A gene for  total baldness  would be epistatic to one for  blond hair  or  red hair . The hair-colour genes are  hypostatic  to the baldness gene. The baldness phenotype supersedes genes for hair colour, and so the effects are non-additive. [ citation needed ]


Example of epistasis in coat colour genetics: If no pigments can be produced the other coat colour genes have no effect on the phenotype, no matter if they are dominant or if the individual is homozygous. Here the genotype "c c" for no pigmentation is epistatic over the other genes. [ 1 ]


Quantitative trait  values after two  mutations  either alone (Ab and aB) or in combination (AB). Bars contained in the grey box indicate the combined trait value under different circumstances of epistasis. Upper panel indicates epistasis between beneficial mutations (blue). [ 10 ] [ 11 ]  Lower panel indicates epistasis between deleterious mutations (red). [ 12 ] [ 13 ]


Since, on average, mutations are deleterious, random mutations to an organism cause a decline in fitness. If all mutations are additive, fitness will fall proportionally to mutation number (black line). When deleterious mutations display negative (synergistic) epistasis, they are more deleterious in combination than individually and so fitness falls with the number of mutations at an increasing rate (upper, red line). When mutations display positive (antagonistic) epistasis, effects of mutations are less severe in combination than individually and so fitness falls at a decreasing rate (lower, blue line). [ 12 ] [ 13 ] [ 14 ] [ 15 ]


The top row indicates interactions between two genes that show either ( a ) additive effects, ( b ) positive epistasis  or ( c ) reciprocal sign epistasis. Below are  fitness landscapes  which display greater and greater levels of global epistasis between large numbers of genes. Purely additive interactions lead to a single smooth peak ( d ); as increasing numbers of genes exhibit epistasis, the landscape becomes more rugged ( e ), and when all genes interact epistatically the landscape becomes so rugged that mutations have seemingly random effects ( f ).


Three sisters


A human spermatozoon fusing with a human ovum. The spermatozoon is approximately 100,000 times smaller in size than the human ovum.


Thomas Hunt Morgan's   Drosophila melanogaster  genetic linkage map. This was the first successful  gene mapping  work and provides important evidence for the  chromosome theory of inheritance . The map shows the relative positions of  alleles  on the second  Drosophila  chromosome. The distances between the genes ( centimorgans ) are equal to the percentages of  chromosomal crossover  events that occur between different alleles. [ 5 ]


Pedigree illustrating Parametric Linkage Analysis


Unlinked Genes vs. Linked Genes


An overview of RNA interference (RNAi) embryonic injection method


Cas12a  in complex with crRNA and target DNA – the key tool for CRISPR screens


Y-DNA haplogroups map of the world


Ancestral haplogroup      Haplogroup A (Hg A)    Haplogroup B (Hg B)  All of these molecules are part of the ancestral haplogroup, but at some point in the past a mutation occurred in the ancestral molecule, mutation A, which produced a new lineage; this is haplogroup A and is defined by mutation A. At some more recent point in the past, a new mutation, mutation B, happened in a person carrying haplogroup A; mutation B defined haplogroup B. Haplogroup B is a subgroup, or  subclade  of haplogroup A; both haplogroups A and B are subclades of the ancestral haplogroup.


Human migrations and mitochondrial haplogroups


Map of human haplotype migration, according to  mitochondrial DNA , with key (coloured) indicating periods in numbered thousands of years before the present.


DNA molecule 1 differs from DNA molecule 2 at a single base-pair location (a C/A polymorphism).


Hardy–Weinberg proportions for two  alleles : the horizontal axis shows the two  allele frequencies   p  and  q  and the vertical axis shows the expected  genotype frequencies . Each line shows one of the three possible genotypes.


Length of  p ,  q  corresponds to allele frequencies (here  p  = 0.6,  q  = 0.4 ). Then area of rectangle represents genotype frequencies (thus  AA : Aa : aa = 0.36 : 0.48 : 0.16 ).


Punnett square for three-allele case (left) and four-allele case (right). White areas are homozygotes. Colored areas are heterozygotes.


A  de Finetti diagram  representing a distribution of genotype frequencies


Time course imaging of two  maize   inbreds  and their  F1 hybrid  (middle) exhibiting heterosis.


Genetic basis of heterosis .   Dominance hypothesis .  Scenario A . Fewer genes are under-expressed in the homozygous individual. Gene expression in the offspring is equal to the expression of the fittest parent.   Overdominance hypothesis .  Scenario B . Over-expression of certain genes in the heterozygous offspring.  (The size of the circle depicts the expression level of gene A)


The origin of IBD segments is depicted via a pedigree.


A colorblind-friendly version of this image.


An IBD segment identified by HapFABIA in Asian genomes. Rare single nucleotide variants (SNVs) that tag the IBD segment are coloured purple. Below the turquoise bar, the IBD segment in ancient genomes is displayed.


A phylogenetic model of introgressive hybridization; the hybrid zone of the two species' lineages is shown in blue, with each horizontal line representing an individual introgressive event.


Lineage fusion on a phylogenetic tree; individual introgression events within the hybrid zone (blue) are shown as horizontal lines. Hybrids are produced before the lineages fuse, but rejoin one of the two lineages. Neither species A nor B remains extant in the area of interest.


Punnett square  for the  agouti  gene in mice, demonstrating a recessive lethal allele. [ 2 ]


Gregor Mendel , the Moravian Augustinian friar who founded the modern science of  genetics


Characteristics Mendel used in his experiments [ 24 ]


P-Generation and F 1 -Generation: The dominant allele for purple-red flower hides the phenotypic effect of the recessive allele for white flowers. F 2 -Generation: The recessive trait from the P-Generation phenotypically reappears in the individuals that are homozygous with the recessive genetic trait.


Myosotis : Colour and distribution of colours are inherited independently. [ 25 ]


F 1  generation: All individuals have the same genotype and same phenotype expressing the dominant trait ( red ). F 2  generation: The phenotypes in the second generation show a 3 : 1 ratio. In the genotype 25 % are homozygous with the dominant trait, 50 % are heterozygous   genetic carriers  of the recessive trait, 25 % are homozygous with the recessive genetic trait and  expressing  the recessive character.


In  Mirabilis jalapa  and  Antirrhinum majus  are examples for intermediate inheritance. [ 28 ] [ 29 ]  As seen in the F 1 -generation, heterozygous plants have " light pink " flowers—a mix of " red " and "white". The F 2 -generation shows a 1:2:1 ratio of  red :  light pink :  white.


A  Punnett square  for one of Mendel's pea plant experiments –  self-fertilization  of the F1 generation


Segregation and independent assortment are consistent with the  chromosome theory of inheritance .


When the parents are homozygous for two different genetic traits ( llSS  and  LL s P  s P ), their children in the F 1  generation are heterozygous at both loci and only show the dominant phenotypes ( Ll S s P ). P-Generation: Each parent possesses one dominant and one recessive trait purebred ( homozygous ). In this example, solid coat color is indicated by  S  (dominant),  Piebald spotting  by  s P  (recessive), while fur length is indicated by  L  (short, dominant) or  l  (long, recessive). All individuals are equal in genotype and phenotype. In the F 2  generation all combinations of coat color and fur length occur: 9 are short haired with solid colour, 3 are short haired with spotting, 3 are long haired with solid colour and 1 is long haired with spotting. The traits are inherited independently, so that new combinations can occur. Average number ratio of phenotypes 9:3:3:1 [ 37 ]


For example 3 pairs of homologous chromosomes allow 8 possible combinations, all equally likely to move into the gamete during  meiosis . This is the main reason for independent assortment. The equation to determine the number of possible combinations given the number of homologous pairs = 2 x  (x = number of homologous pairs)


Workflow of microfluidic whole genome chromosome isolation and amplification. Not at scale


Figure 1 : Inheritance pattern of dominant ( red ) and recessive (white) phenotypes when each parent (1) is homozygous for either the dominant or recessive trait. All members of the F 1  generation are heterozygous and share the same dominant phenotype (2), while the F 2  generation exhibits a 6:2 ratio of dominant to recessive phenotypes (3).


Mirabilis jalapa


Carl Correns


Co-dominant expression of genes for plumage colours.


In the genepool of cats ( Felis catus ) there is a recessive allele for orange coat on the X-Chromosome. In a male the Y-Chromosome cannot compensate this, so a tomcat with that allele is born orange. This allele is  epistatic  over some other coat color genes. [ 5 ] [ 6 ]


A heterozygous cat with kittens from an orange tomcat: 50 % are orange, 50 % can produce  eumelanin . Here the segregation of her two alleles, one dominant for the ability to produce eumelanin, one recessive for orange, was crucial for the colour of the kittens. With the young males it is decisive which of the two X-Chromosomes they received from the mother, because the Y-Chromosome does not contain a corresponding allele from the father. In the young females it is also decisive which X-Chromosome they got from the mother, because they each have an allele for orange from the father and only homozygotes become orange.


Example of a pedigree for a genetic trait inherited by mitochondrial DNA in animals and humans. Offspring of the males with the trait don't inherit the trait. Offspring of the females with the trait always inherit the trait (independently from their own sex).


A comparison of a mouse unable to produce  leptin  thus resulting in obesity (left) and a normal mouse (right)


Sickle cell anemia overdominance


Overview of paleopolyploidy process. Many higher eukaryotes were paleopolyploids at some point during their evolutionary history.


A diagram that summarizes all well-known paleopolyploidization events.


Detection of paleopolyploidy using Ks.


Gregor Mendel , the Father of Genetics


William Bateson


Ronald Fisher


Example of a pedigree chart using  Ahnentafel  numbering


Pedigree of horse Shagya IX b. 1895


Eye color is an example of a (physical) phenotypic trait


A haploid set that consists of a single complete set of chromosomes (equal to the monoploid set), as shown in the picture above, must belong to a diploid species. If a haploid set consists of two sets, it must be of a tetraploid (four sets) species. [ 1 ]


A comparison of  sexual reproduction  in predominantly haploid organisms and predominantly diploid organisms. 1)  A haploid organism is on the left and a diploid organism is on the right. 2 and 3)  Haploid egg and sperm carrying the dominant purple gene and the recessive blue gene, respectively. These gametes are produced by simple mitosis of cells in the germ line. 4 and 5)  Haploid sperm and egg carrying the recessive blue gene and the dominant purple gene, respectively. These gametes are produced by meiosis, which halves the number of chromosomes in the diploid germ cells. 6)  The short-lived diploid state of haploid organisms, a zygote generated by the union of two haploid gametes during sex. 7)  The diploid zygote which has just been fertilized by the union of haploid egg and sperm during sex. 8)  Cells of the diploid structure quickly undergo meiosis to produce spores containing the meiotically halved number of chromosomes, restoring haploidy. These spores express either the mother's dominant gene or the father's recessive gene and proceed by mitotic division to build a new entirely haploid organism. 9)  The diploid zygote proceeds by mitotic division to build a new entirely diploid organism. These cells possess both the purple and blue genes, but only the purple gene is expressed since it is dominant over the recessive blue gene.


Karyogram  of a typical human cell, showing a diploid set of 22  homologous   autosomal  chromosome pairs. It also shows both the female (XX) and male (XY) versions of the two  sex chromosomes  (at bottom right), as well as the  mitochondrial genome  (to scale at bottom left).  Further information:  Karyotype


Example of a genome-wide scan for QTL of  osteoporosis


This image shows haploid (single), diploid (double), triploid (triple), and tetraploid (quadruple) sets of chromosomes. Triploid and tetraploid chromosomes are examples of polyploidy.


Organ-specific patterns of endopolyploidy (from 2 x  to 64 x ) in the giant ant  Dinoponera australis


This  phylogenetic tree  shows the relationship between the best-documented instances of  paleopolyploidy  in eukaryotes.


Schematic  karyogram  of a human, showing the normal  diploid  (that is, non-polyploid)  karyotype . It shows 22  homologous chromosomes , both the female (XX) and male (XY) versions of the  sex chromosome  (bottom right), as well as the  mitochondrial genome  (to scale at bottom left). Further information:  Karyotype


Speciation  via polyploidy: A  diploid  cell undergoes failed  meiosis , producing diploid  gametes , which self-fertilize to produce a tetraploid  zygote .


Schematic phylogeny of the Chromalveolata. Red circles indicate polyploidy, blue squares indicate hybridization. From Albertin and Marullo, 2012 [ 89 ]


Testing substance (PTC) structure: Phenylthiocarbamide/  Phenyl-thio-carbamide/ Phenylthiourea


PTC molecule


Synteny (in the modern sense) between human and mouse chromosomes. Colors in the human chromosomes indicate regions homologous with parts of the mouse chromosome of the same color. For instance, sequences homologous to mouse chromosome 1 are primarily on human chromosomes 1 and 2, but also 6, 8, and 18. The X chromosome is almost completely syntenic in both species. [ 1 ]


Synteny of Hox gene clusters; lines indicate homology


Punnett squares showing typical test crosses and the two potential outcomes. The individual in question may either be heterozygous, in which half the offspring would be heterozygous and half would be homozygous recessive, or homozygous dominant, in which all the offspring would be heterozygous.


Drosophila melanogaster


Experimental cross performed by  Thomas Hunt Morgan , illustrating the X-linked inheritance of  white  in  Drosophila . [ 3 ]


Unlike culinary  bananas , wild-type bananas have numerous large, hard seeds.


Y-linked inheritance


Pedigree tree showing the inheritance of a Y-linked trait


Homozygous and heterozygous


Schematic  karyogram  of a human, showing a diploid set of all chromosomes, except in case of the  sex chromosomes  in males (bottom right), where there is an  X chromosome  and a much smaller  Y chromosome , which does not have all the genes that the X chromosome has, making a male hemizygous for those genes.  Further information:  Karyotype


Heterozygosity values of 51 worldwide human populations. [ 10 ]   Sub-Saharan Africans  have the highest values in the world.


A  karyotype  of an individual with  trisomy 21 , showing three copies of chromosome 21.


The three major single-chromosome mutations: deletion (1), duplication (2) and inversion (3).


The two major two-chromosome mutations: insertion (1) and translocation (2).


Increase in frequency over time of genotype

 A

 {\displaystyle A}

 , which has a 1% greater relative fitness than the other genotype present,

 B

 {\displaystyle B}


Herbert Spencer


Foxp2  is expressed in the developing cerebellum and the hindbrain of the embryonic day 13.5 mouse.  Allen Brain Atlases


Human  FOXP2  gene and evolutionary conservation is shown in a multiple alignment (at bottom of figure) in this image from the  UCSC Genome Browser . Note that conservation tends to cluster around coding regions ( exons ).


The  FOXP2  gene is located on the long (q) arm of  chromosome 7 , at position 31.


Figure 1: Genetic distance map by Cavalli-Sforza et al. (1994)  [ 1 ]


Figure 2: Divergence timeline between two hypothetical species.


Figure 4: A diagram showing the relationship between DNA base-pairs and the type of mutation needed to convert each base to another based on the Kimura 2 parameter substitution model.


Figure 5: A diagram showing the relationship between DNA base-pairs and the type of mutation needed to convert each base to another based on the Kimura 3 parameter substitution model.


Figure 6: Euclidean genetic distance between 51 worldwide human populations, calculated using 289,160  SNPs . [ 30 ]  Dark red is the most similar pair and dark blue is the most distant pair.


Figure 7: Representation of path between points that is calculated for the Czekanwski (Manhattan) distance formula.


Figure 8: Representation of path between points that is calculated for the Roger's distance formula.


A graphical representation of the typical human  karyotype .


Varieties of  maize  in the office of the Russian plant geneticist  Nikolai Vavilov


A  Tanzanian cheetah .


Photomontage  of planktonic organisms.


A  De Finetti diagram  visualizing genotype frequencies as distances to triangle edges x (AA), y (Aa) and z (aa) in a  ternary plot . The curved line are the  Hardy–Weinberg equilibria .


A  Punnett square  visualizing the genotype frequencies of a  Hardy–Weinberg equilibrium  as areas of a square.  p  (A) and  q  (a) are the  allele frequencies .


The process showing how mother's curse occurs. mtDNA mutates and generates copies that are detrimental for females (red) and copies that only detrimental for males (blue). Mitochondria bad for females are selected against, while mitochondria only bad for males are transmitted to the offspring. As a result, the males of offspring who inherit bad mutations would have a lower fitness.


Illustration of chromosome crossover during genetic recombination


Simple genotype–phenotype map that only shows additive pleiotropy effects. G1, G2, and G3 are different genes that contribute to phenotypic traits P1, P2, and P3.


Pleiotropy seems limited for many traits in humans since the SNP overlap, as measured by variance accounted for, between many polygenic predictors is small.


Peacock with albinism


The blood of a two-week-old infant is collected for a PKU screening.


Photomicrograph of normal-shaped and sickle-shape red blood cells from a patient with  sickle cell disease


Patient with Marfan Syndrome


Chicken exhibiting the frizzle feather trait


Unequal Crossing Over


Azadirachta indica  (Neem)


Piñatex logo, by Ananas Anam


Ayahuasca cooking


Ayahuasca being prepared in the  Napo  region of  Ecuador


Ayahuasca cooking in the  Loreto  region of  Peru


Ayahuasca being prepared in  Ecuador


B. caapi   inflorescence


Syrian rue  seeds can be used to provide an MAOI.


Molecular structure of  harmine


Molecular structure of  harmaline


Molecular structure of  tetrahydroharmine


Parties to the convention      Signed, but not ratified      Non-signatory


COP13 Mexico meeting


COP15 Canada meeting


Annonin -based biopesticides, used to protect crops from beetles and other pests, were developed from the plant  Annona squamosa . [ 19 ]


The  tuberculosis  drug  streptomycin  was discovered from the  actinomycete   Streptomyces griseus . [ 10 ]


Halichondrin B , an example of a structurally complex and medically important natural product [ 34 ]


Zingiber officinale , an example of a medicinal plant used in multiple cultures [ 37 ]


Voucher deposition allows species identity to be re-evaluated if there are problems re-isolating an active constituent from a biological source. [ 10 ]


A white rosy periwinkle


A neem tree


The Enola bean


The succulent  Hoodia gordonii


Parties to the CBD [ 79 ]      Signed, but not ratified [ 79 ]      Non-signatory [ 79 ]


Cannabis  growing as  weeds  at the foot of  Dhaulagiri ,  Nepal


A  thicket  of wild  cannabis  in  Islamabad ,  Pakistan


Cannabis  female flower with visible  trichomes


Male  Cannabis  flower buds


Underside of  Cannabis sativa  leaf, showing diagnostic venation


Top of  Cannabis  plant in vegetative growth stage


Relative size of varieties of  Cannabis


Cannabis ruderalis


Three theories of classification for  Cannabis . From left to right, monotypic with three subspecies (A), polytypic consisting of up to three species (B), and single phenotypically diverse species (C).


Comparison of physical harm and dependence regarding various drugs [ 103 ]


A dried bud, typical of what is sold for recreational use


Cannabis sativa  stem longitudinal section


Cannabis Museum  in  Amsterdam


Cannabis  leaf pictured in the coat of arms of  Kanepi Parish


People marching in the streets of  Cape Town  against the prohibition of cannabis in  South Africa , 9 May 2015


The Dagga Couple (seated) with Jeremy Acton of the Dagga Party


Cape Town Cannabis Walk 2017


Male  Cannabis sativa  in flower


A female sativa cannabis strain in flowering or "budding" stage


Δ 9 - tetrahydrocannabinol  (THC)


Cannabis sativa , scientific drawing from c. 1900


White Widow


A flowering  cannabis  plant


Blue Dream


Sour Diesel


Only a few of the many varieties of  potato  are commercially grown; others are heirlooms.


A selection of heirloom tomatoes


A hemp field in  Côtes-d'Armor ,  Brittany , France, which is Europe's largest hemp producer as of 2022


Hemp seed


A  macro  image of hemp seeds


Hemp and bead jewelry


Hemp rope


Hemp straw animal bedding


Biodiesel sample


The variety of appearances for cannabis. Only  C. sativa  (left) is suited for industrial hemp, but it also has medicinal varieties.


Dried hemp stalks displayed at the International Hemp Fair in  Vienna


Harvesting hemp in the USSR, 1956


Cannabis sativa  from  Vienna Dioscurides , 512 AD


Hemp being grown in Oregon in 2020


Hemp was classified as a drug and heavily debated and prohibited through the 20th century through 2018.


Japanese  Shinto shrine  with rope made of hemp


International waters are the areas shown in dark blue in this map, i.e. outside  exclusive economic zones , which are in light blue.


Marine protected areas as of 2020 (data from MPAtlas). [ 40 ]


The Laguna Miramar in the Lacandon Jungle


Field cut from the jungle near  Frontera Corozal


Maca plants


Maca root powder


Alpaca   manure  is used to fertilize maca croplands


(1 R ,3 S )-1-Methyltetrahydro-carboline-3-carboxylic acid found in maca


National biodiversity strategies that align with Aichi Target 9 (invasive species and pathways are identified and prioritized, priority species are controlled or eradicated and measures are in place to prevent their introduction and establishment)


Vandana Shiva , one of the founders of Navdanya (2014)


Flowers


Plant


Green rooibos tea


Rooibos tea in a glass


Rooibos tea with milk


A rooibos-infused liqueur and rooibos tea


A. linearis  response to fire. Plants native to the  Fynbos eco-region , like rooibos, are fire dependent, but rooibos varieties exhibit two different adaptions to fire.


Vandana Shiva in  Cologne, Germany , in 2007


Henri Ernest Baillon , publisher of the name  Tabernanthe iboga .


Bark of  Tabernanthe iboga


Shredded bark of  Tabernanthe iboga  for consumption. Contains ibogaine.


Plenary meeting of UNPFII (2015)


Maria Eugenia Choque Quispe , a member of the UN Permanent Forum on Indigenous Issues, speaks at the body's 2015 session.


President and CEO Sharon F. Terry in 2017


Differences in the standard methods for DNA barcoding and metabarcoding. While DNA barcoding focuses on a specific species, metabarcoding examines whole communities.


Applications of environmental DNA metabarcoding in aquatic and terrestrial ecosystems  [ 10 ]


Emerging insect DNA sources used in metabarcoding  [ 18 ]


Global ecosystem and biodiversity monitoring with environmental DNA metabarcoding  [ 10 ]


Six steps in DNA barcoding and metabarcoding  [ 30 ]


History of sequencing technology  [ 42 ]


Questions for consideration in the design and implementation phases of an environmental DNA metabarcoding study  [ 13 ]