problem 2

Question 1

allele

Answer 1

Variant form of a given gene. Different alleles can result in different observable phenotypic traits

Question 2

homozygous

Answer 2

having 2 copies of the same allele (AA/ aa)

Question 3

heterozygous

Answer 3

having 2 copies of different alleles (Aa)

Question 4

blending inheritance

Answer 4

Inheritance of traits from 2 parents (black and blond hair) produces offspring with characteristics that are intermediate / a mixture between those of the parents (brown hair)

Question 5

single-gene characteristic

Answer 5

any characteristic where allelic variation in a single gene accounts for differences in the phenotype

one gene –> one effect

Question 6

polygenetic trait

Answer 6

Traits are polygenic when there is wide variation in them and each (dominant) allele “adds up” to the expression of the trait (i.e. if you have many alleles that code for height they add up and contribute to the overall big height)

Question 7

co-dominance

Answer 7

heterozygotes fully express the phenotype of both of their homozygous parents (i.e. blood groups like AB)

Question 8

incomplete dominance

Answer 8

phenotype of the heterozygote is intermediate in form between those of the two homozygotes (i.e. red homozygote + white homozygote = pink flower), the third phenotype is a combination of the phenotypes of both alleles

Question 9

linkage

Answer 9

Tendency of DNA sequences that are close together on a chromosome to be inherited together during meiosis. The closer together on a chromosome, the less the chance of recombination between them

Question 10

law of segregation

mendel

Answer 10

Allele pairs randomly separate / segregate during gamete formation and randomly unite at fertilization, each gamete carries only one allele for each gene

Question 11

law of dominance

mendel

Answer 11

Recessive alleles will always be masked by dominant ones, therefore only the dominant phenotype will be expressed, while still having a heterozygote genotype

Question 12

law of independent assortment

mendel

Answer 12

When 2 or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits and equal opportunity of occurring together (wrinkles or smooth and yellow or green)

Question 13

Hardy-Weinberg equilibrium

Answer 13

states that allele + genotype frequencies in a (perfect) population will remain constant from generation to generation in absence of other evolutionary inferences
- large population, no mutations, random mating, no natural selection, no gene flow

p+q=1; p2+2pq+q2=1

Question 14

independent segregation

Answer 14

happens when genes for two characteristics lie on different chromosomes – if on same chromosome, they exhibit linkage (travel together until broken apart by recombination)

e.g. color + texture

Question 15

neutral theory of molecular evolution

Answer 15

holds that at the molecular level most evolutionary changes and most of the variation within and between species is not caused by natural selection but by genetic drift of mutant alleles that are neutral

Question 16

genetic amplification

Answer 16

an increase in the number of copies of a gene without proportional increase in other genes

Question 17

quantitative genetics

Answer 17

Branch of population genetics that deals with continuously varying phenotypes as opposed to discretely identifiable phenotypes and gene products (predicting phenotypes which are not either/or)

Question 18

polygenetic inheritance

Answer 18

a sum of genes can be inherited differently but the single alleles that contribute follow the mendelian laws

Question 19

inbreeding

Answer 19

production of offspring

Question 20

genetic drift

Answer 20

Variation in the relative frequency of different genotypes in a small population, due to the chance of disappearance of genes as individuals die or don’t reproduce

Question 21

heritability

Answer 21

estimation of the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population

Question 22

coefficient of relatedness = r

Answer 22

Probability that 2 individuals share an allele due to common ancestry, ranges from 0 (unrelated) to 1 (clones)

Question 23

behavioral genetics

Answer 23

Research that uses genetic methods to investigate the nature + origins of individual differences in behavior

Question 24

monozygotic twins

dizygotic twins

Answer 24

identical twins (100%)

non-identical twins (50%)

Question 25

falconer’s estimate of heritability

Answer 25

Formula used to determine the genetic heritability of a trait based on the differenced between twin correlations (correlation of MZ twins being higher than the one of DZ twins)

2(r(monozygotic twins) – r(dizygotic twins) = estimated heritability

Question 26

ACE model

Answer 26

Epidemiological model that states that individual differences in a phenotype are accounted by A (additive genetic factors), C (common environmental factors), and E (specific environmental factors)

Question 27

epistatic effects

Answer 27

gene = epistatic when its presence supresses the effect of a gene at another locus. Also called inhibitory genes

Question 28

narrow-sense heritabilities

Answer 28

heritability estimates(variance) based on additive genetic effects (A) (study designs include only A, C, and E) = h2

Question 29

broad-sense heritabilities

Answer 29

Estimates of variance that include epistatic effects (all genetic factors) = H2

Question 30

coefficient of additive genetic variance

Answer 30

estimate of the amount of genetic variation in a population relevant to a particular trait, independent of the amount of environmental variation

Question 31

complex traits

Answer 31

Trait that does not follow Mendelian inheritance patterns, likely derived from multiple genes + exhibits a large variety of phenotypes

Question 32

liability thresholds

Answer 32

when a certain threshold is reached you develop a disease, because you have too many genes coding for that disease

Question 33

genetic amplification

Answer 33

increase in number of copies of a gene without an increase in other genes