[17.7-8] autosomal linkage, epistasis

Question 1

what is an autosome?

Answer 1

the remaining 22 chromosome other than the sex chromosomes

Question 2

what is autosomal linkage?

Answer 2

where two or more genes are carried on the same autosome

Question 3

how might genes on the same chromosome be inherited together?

Answer 3

• if there is no crossing over
• they are therefore not segregating in accordance with mendel’s law of independent assortment

Question 4

what is recombination frequency?

Answer 4

• frequency with with a single chromosomal crossover will take place between two genes during meiosis
• this is always displayed as a percentage of the total number of offspring

Question 5

describe the punnett square for heterozygous characteristics

Answer 5

• normal 2x2
• eg. genotype = GGNN, GgNn, GgNn, ggnn

Question 6

how can you map out where alleles are found on the chromosome?

Answer 6

• recombination freq = relative separation distance
• on a horizontal line representing the chromosome, mark the two loci with the largest separation with the phenotypes
• mark the possible positions of the other loci by triangluating possible psoitions

Question 7

what is epistasis?

Answer 7

when the allele of one gene affects the expression of another in the phenotype

Question 8

describe the punnet square for the F2 genotypes based on AABB and aabb parental genotypes

Answer 8

• 4x4 grid
• gametes = AB, Ab, aB, ab
• ratio = 9:3:4 (but probs depends on q)