"Colourless"

A recessive condition resulting from a null allele. Proteins necessary for producing melanin, a dark pigment, are absent.

aka Dominance series

An arrangement of multiple alleles by order of dominance. Equal signs signify incomplete dominance or codominance. Describes the hierarchy of multiple alleles. Null alleles are often the most recessive. Hypomorphic alleles are often in the middle. Wild type alleles are often the most dominant.

"Other"

Polyploids formed by hybridization between different species. More likely to be fertile than autopolyploids because the two sets of chromosomes are dissimilar and more likely to pair regularly. 

2n = 26

Originated in Peru. Crossed with Old World cotton to produce upland cotton.

"Not good fold"

One chromosome or chromosome segment is over or under-represented. Creates a genetic imbalance that produces a phenotypic effect. Hypopoloid or hyperploid.

"Self"

Polyploids created by crossing within one species. A single genome is muliplied to create extra sets of chromosomes. In plants there is more vegetative growth: larger cells, thicker laves, bigger flowers, larger plants, bigger fruits, less seed production.

"Eat bacteria"

aka Bacterial virus

Inject DNA into a bacterium so that it will produce progeny phages. Virulent or temperate. Includes bacteriophages T4 and lambda.

Triticum aestevium

6n = 42

A hexaploid formed from two formations of allopolyploids: the first cross between wild einkorn and wild barley, producing emmer wheat, the second cross between emmer wheat and Triticum tauschii. This produced a 3n = 21 individual, and the chromosomes were doubled. There are many varieties, including: hard red spring wheat, hard red winter wheat, soft red winter wheat, hard white wheat, and soft white wheat.

Plural, chiasmata

"Cross"

Points where non-sister chromatids crossover, producing recombination. Vestigal evidence of DNA exchange: entanglements created by earlier crossover events. Prevents chromatids from separating too soon, minimizing nondisjunction.

aka Plaque

A visible accumulation of bacteriophages that can form on bacterial cultures within hours of infection.

Colicinogenic factor

A plasmid which encodes proteins that kill sensitive E. coli cells. Some enable conjugation.

aka Complete recessiveness

AA and Aa have one phenotype, and aa has another. A 3:1 ratio is observed from a monohybrid cross. A 9:3:3:1 ratio is observed from a dihybrid cross.

"Of the same blood"

Matings between relatives. Rare in humans, depending on cultural traditions.

aka Cis configuration

"Same side"

AB/ab

A linkage phase. Both dominant alleles are inherited from one parent, and both recessive alleles are inherited from the other parent.

46, del(5)(p14)

"Cry of the cat"

A deletion in chromosome 5 on the short arm. Severe mental and physical impairment with a plaintive, cat-like cry during infancy.

aka Physical mapping

A type of chromosome map. Mapping of genes using markers and banding on chromosomes. Done by analyzing deletions and duplications on different loci in a heterozygote. Thoroughly developed in Drosophila dueto studies in polytenes. Includes deletion and duplication mapping.

Deoxyadenosine monophosphate

The nucleotide of adenine.

Jimson weed

It has 12 pairs of chromosomes, and 12 different trisomies. Albert Blakeslee and JohnBelling studied aneuploidies in this plant.

Deoxycytidine monophosphate

The nucleotide of cytosine.

aka Deficiency

Hypoploidy with a missing chromosome segment. Causes a phenotypic effect. Large deletions can be studied cytologically. In Drosophila, deletions can be studied in polytenes. Incldues Cri-du-chat syndrome.

Deoxyguanosine monophosphate

The nucleoside of guanine.

"Two fold"

Two alleles for each gene coexist in each cell. The adults of most eukaryotes are diploid. Most somatic cells contain two copies of the haploid genome.

"Two"

A cross that looks at two traits simultaneously. Shows that traits are not inherited together. Produces a phenotypic ratio of 9:3:3:1.

Deoxyribonucleic acid

A nucleic acid. The genetic material of virtually all organisms. First discovered by Friedrich Miescher. Structure was discovered by Watson and Crock. A right-handed double helix of polynucleotide strands, with hydrogen bonds holding the strands together. There is a major groove and a minor groove. Contains deoxyribose sugar, and the nitrogen-containing bases adenine, guanine, cytosine, and thymine. The two strands are anti-parallel and complementary. Has the ability to duplicate itself. It is housed in the nucleus and during cell division it is compacted into the chromosomes. One person has around 3 billion nucleotides in their DNA. DNA directs the function of RNA. Functional DNA is supercoiled.

Equus asinus

2n = 62

Crossed with a horse to produce a mule.

47, +21

Trisomy in chromosome 21. The only autosomal chromosome nondisjunction disorder with adult survivors, and the best known trisomy in humans. First descrbed in 1866 by Langdon Down, but wasn't understood until 1959. Occurs in 1/700 people. 96% of cases are due to meiotic nondisjunction events: 80% of these in oogenesis in the mother, and 20% in spermatogenesis in the father. The longer the prophase arrest in the mother (the older the mother), the higher the  likelihood of Down syndrome. Short stature, loose and hyperflexible joints (especially ankles), broad skulls, wide nostrils, large tongues with distinctive furrowing, epicanthal folds, stubby hands with a crease in the palm, impaired mental abilities requiring special education and care, a reduced lifespan, and early onset of Alzheimer's disease at age 40 - 50.

Fruit flies

A test organism that has been used to centuries. There are four pairs of chromosomes, one of which are sex chromosomes. Two pairs of the autosomes are large and metracentric; the other pair is small and dot-like.

47, + 18

Trisomy in chromosome 18. Occurs in 1/8,000 people. Serious phenotypic abnormalities which cause death within a few weeks: congenital malformation of many organs including brain and heart, low-set and malformed ears, receding mandible, small mouth and nose with an elven appearance, mental deficiency, horseshoe or double kidney, short sternum, clenched hands, rocker bottom feet. 90% of individuals die within the first six months after birth.

Triticum turgidum

4n = 28

Produced froma cross between wild einkorn and wild wheat. Cultivated for 10,000 years. High protein, low lysine, does poorly in poor soils. There are many varieties, including durum wheat. Crossed with Triticum tauschii to produce bread wheat. Crossde with rye to produce triticale.

"Stand above"

When one allele masks the genotype of another. The epistatic gene masks the hypostatic gene. Can be recessive or dominant. Example: cinnabar mutation in Drosophila is epistatic over the white gene.

E. coli

A bacteria. Infected by bacteriophages T4 and lambda. Can use almost any sugars as an energy source. Some mutants are unable to grow on certain sugars alone. Some mutants are resistant to antibiotics. Wild-types are prototrophs, and some mutants are auxotrophs.

"True"

Chromatin that dyes a light colour.

Fertility factor

A plasmid that codes for an F pili on the donor cell in cojugation. About 10⁵ nucleotides in size. May be in an autonomous state or integrated state.

"Woman-man forms"

Drosophila flies with male and female structure.

aka Prognatism

Normal varitations in the size of the mandible can be pathological if extreme. Frequent in the Habsburg royal family, peaking at Phillip II and Charles I of Spain; the family was inbred. It is clearly a heritable trait, but details are unknown. Authors studied 2,562 individuals from 55 families. Most pedigrees suggest autosomal dominant inheritance with incomplete penetrance. There is a major gene that influences expression of prognatism with clear signs of Mendelian inheritance and a multifactorial component. Has low heritability.

Predicts genotypes through alleles frequencies of a population. Allele frequencies stay constant if there are no evolutionary influences: non-random mating, unequal survival, population subdivision, and migration.

f(A) = p

f(a) = q

p² + 2pq + q² = 1

"Different"

Chromatin that dyes a dark colour.

"Six fold"

Having six sets of chromosomes. Oats and bread wheat are hexaploid.

c^hc^h

A rabbit coat colour. A temperature sensitive mutation. In rabbits reared at 20ºC or lower, dark pigment is produced at theextremities of the rabbit: ears, face, and legs. In rabbits reared at higher temperatures, the coat is white all over. The enzynme that produces the dark pigments is inactivated and higher temperatures.

aka Homologs

Chromosome containing the same genetic code for the same traits, together in a pair in a diploid cell.

AA

Having two dominant alleles. ONe of the P generation parents is homozygous dominant. 25% of F2 indivuduals are homozygous dominant.

aa

Having two recessive alleles. One of the P generation parents is homozygous recessive. 25% of F2 individuals are homozygous recessive.

Equus caballus

2n = 64

Crossed with a donkey to produce a mule.

"Over-fold"

Aneuploidy where a chromosome or chromosome segment is over-represented.

"Beneath form"

A partially functional allele. A poorly functioning protein a produced, or reduced amounts of a normally functioning protein is produced. A mild mutant phenotype.

"Under-fold"

Aneuploidy where a chromosome or chromosome segment is under-represented.

Invented by Sewall Wright in 1921. Involves the analysis of correlations between individuals in a pedigree. In the 1940s Charls Cotterman showed that it is the same as the probability of identity by descent. An increased F value results in increase in probability of recessive disorders. It can be used to measure the decline in complex phenotypes, by graphing phenotypes with F as the x-axis; traits decline linearly. To find F of an inbred individual.

1. Identify common ancestor(s) of inbred individual, connected to both parents.

2. Count the number of individuals in each inbreeding loop (one loop for each common ancestor). Do not count the inbred individual.

3. Calculate ½ⁿ, and add up these values for each inbreeding loop

4. If the common acnestor is inbred, multipy ½ⁿ b (1+F_CA), where F_CA is the F value of the common ancestor. This accounts for the possibility that the genes are already identical by descent.

aka Partial dominance

When a heterozygote has a different phenotype from either the dominant or recessive homozygote. Includes semidominant. Produces a 1:2:1 ratio from a monohybrid cross.

Bovine spongiform encephalopathy (PSE)

A disease that destroys brain tissues and leads to death in cattle. In sheep and goats it is called scrapie. Caused by prions. Can be passed to humans by eating meat from infected cattle. In humans it is called Creutzfeldt-Jakob disease. All animals have the normal prion, PrP^C. The disease form of the prion is PrP^Sc, and it converts helathy prions into diseased prions and accumulates int he brain, causing nerve cells to die, leading to a "spongy" appearance of the brain tissue.

A recessive lethal allele in cats that also affects tail development.

mm: normal cat

Mm: Manx cat

MM: lethal

Mendel's Second Law

Different genes are inherited separately from one another. Mendel showed this with dihybrid crosses. There are many possible ways for chromosomes to be separated during anaphase of meiosis in heterozygous individuals, each equally likely.

 Mendel's First Law

Alleles are passed on to offspring unchanged, and segregate into gametes independently. During meiotic division, homologous chromosomes pair, and in anaphase they separate and move to opposite poles.

M phase

One of the phases of cell cycle. Includes prophase, prometaphase, metaphase, anaphase, and telophase. Produces clone daughter cells. All organisms use mitosis to grow and repair themselves.

"One"

A cross that looks at one gene.

2n = 63

Sterile. Created from a cross between a donkey and a horse. Hardy and strong. Farm mechanization caused a rapid decline in mule production.

aka Multistrand model

Many strands of DNA run parallel through the chromosome. There is no evidence to support this model.

Amorphic allele

"Without form"

A non-functional allele. Almost always recessive. The protein product is not produced, or a non-functional protein is produced. Example: cinnabar mutation in drosophila. Null alleles can be dominant when there is haploinsufficiency.

"Eight fold"

Having eight copies of the haploid genome. Commercial varieties of strawberries, and sugarcanes are ocatploid.

Inbred individuals

F = 1/8

Inbred individuals

F = 1/16

Inbred individuals with two common ancestors: the grandparents. There is one inbreeding loop in the pedigree.

F = 1/4

Inbred individuals with one common ancestor: the common grandparent. There is one inbreeding loop in the pedigree.

F = 1/8

Inbred individuals

F = 1/8

2n = 26

Originated in Asia and Africa. Crossed with American cotton to produce upland cotton.

Origin of Transfer

The site in an F factor where DNA replication for transfer in conjugation is initiated.

47, + 13

Trisomy in chromosome 13. Occurs in 1/20,000 births. Serious phenotypic abnormalities that cause death in a few weeks: mental deficiency, deafness, minor muscle seizures, cleft lip and/or palate, cardiac abnormalities, posterior heel prominence, large triangular nose, malformation of the brain and heart, polydactyly.

"Five fold"

Having five sets of chromosomes. Some seedless varieties of citrus are pentaploid.

Trait

The appearance or manifestation of a characteristic. Conferred by genotype. It has some measure of penetrance and some measure of expressivity. One genotype can have a wide norm of reaction.

Beta sheet

A secondary structure in proteins. Formed by looping of the polypeptide back on itself, held together with hydrogen bonds.

"To take many turns"

When one gene affects many (seemingly unrelated) aspects of phenotype. The result of complex interactions between biochemical pathways. Examples: PKU, singed mutation, sickle cell disease, cystic fibrosis.

"Fold"

The number of complete chromosome sets.

"Many fold"

Having more than two copies of the haploid genotype. 30% - 35% of plants are polyploid. Rare in animals because it interferes with sex determination: certain fish and amphibians are polyploid. In plnats, cell size and organism size is increased; the plant produces larger seeds and fruits, and they are often used in agriculture: wheat, coffee, potatoes, bananas, strawberries, cotton, ornamentals. Many polyploids are sterile: chromosomes separate irregularly in meiosis, leading to aneuploidy gametes. Polyploid plants usually reproduce asexually.

"Many threads"

A bundle of chromosomes aligned in parallele. Chromosomes are stuck in interphase. Found in many insect species including mosquitoes and Diptera. In Drosophila the chromosomes pair and form 9 rounds of replication, and form perfect alignments, with all the centromeres converging at the chromocentre. Calvin Bridges studied polytenes in Drosophila.