Task 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 two copies of the same allele (AA or aa)

Question 3

Heterozygous

Answer 3

Having two 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

characteristic

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

Question 6

Polygenic 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

Dominant

Answer 7

A gene that is expressed phenotypically in heterozygous or homozygous individuals

Question 8

Recessive

Answer 8

A gene that is phenotypically expressed in the homozygous state but has its expression masked in the presence of a dominant gene

Question 9

Punnet square

Answer 9

Square diagram used to predict an outcome of a particular cross or breeding experiment and determine the probability of an offspring having a particular genotype (and the resulting phenotype)

Question 10

Co-dominance

Answer 10

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

Question 11

Incomplete dominance

Answer 11

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 12

Linkage

Answer 12

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 13

Law of segregation

Answer 13

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

Question 14

Law of dominance

Answer 14

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

Question 15

Law of independent assortmen

Answer 15

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 16

Hardy- Weinberg equilibrium

Answer 16

Model of change in expected frequencies of alleles over generations, states that allele and genotype frequencies in a (perfect) population will remain constant from generation to generation in the absence of other evolutionary influences.
p+q=1 and p2+2pq+q2=1

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

Polygenic 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

Answer 22

Probability that 2 individuals chare an allele due to common ancestry, expressed by symbol r, ranges from 0 (unrelated) to 1 (clones)

Question 23

Behaviour genetics

Answer 23

Research that uses genetic methods to investigate the nature and origins of individual differences in behaviour

Question 24

Monozygotic twins

Answer 24

Identical twins that form when a single fertilized egg splits

Question 25

Dizygotic twins

Answer 25

Sibling produced by the same pregnancy, developed from separate eggs each fertilized by a different sperm cell

Question 26

Shared environmental influences

Answer 26

Factors that will influence both twins regardless of MZ or DZ like parental social class, parental behaviour, diet available, the school attended, or the house grown up in.

Question 27

Non-shared environmental influences

Answer 27

Influences that are neither shared by MZ nor by DZ twins such as childhood diseases or accidents that affected one twin and not the other like a disease or an accident

Question 28

Falconer’s estimate of heritability

Answer 28

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 29

ACE models

Answer 29

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 30

Epistatic effects

Answer 30

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

Question 31

Narrow-sense heritabilities

Answer 31

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

Question 32

Broad-sense heritabilities

Answer 32

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

Question 33

Coefficient of additive genetic variance

Answer 33

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

Question 34

Complex traits

Answer 34

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

Question 35

Liability thresholds

Answer 35

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

Question 36

Genetic amplification

Answer 36

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