Linkage & recombination

Question 1

Linkage

Answer 1

If genes are less that a certain distance apart on a chromosome they are linked and will NOT assort independently

Question 2

Recombination

Answer 2

occurs through crossing over of arms of homologous chromosomes in a bivalent

Question 3

Chiasma

Answer 3

is the site of crossing over

Question 4

Crossing over occurs in

Answer 4

prophase I

Question 5

Chromosome mapping

Answer 5

(number of recombinants / total progeny) x 100%

Add observed number of recombinants and divide by total

Question 6

Genes A and B are independently assorting

Answer 6

4 classes of offspring with a 9:3:3:1 ratio

Question 7

Genes A and B are tightly linked

Answer 7

crossing over does not occur; ~2 classes of offspring with a ~3:1 ratio (inherits like a single gene cross)

Question 8

Genes A and B are linked

Answer 8

crossing over occurs, variations in the 3:1 ratio

Question 9

Map distance is capped at

Answer 9

50 cM cannot observe more than 50% recombination

Question 10

Recombination fraction = independent assortment

Answer 10

TRUE

Question 11

Cis -

Answer 11

both dominant alleles are on one chromosome and both recessive are on the other

Question 12

Trans

Answer 12

one of each. =- Opposite of cis

Question 13

Nail-patella syndrome

Answer 13

rare dominant allele, N, on chromosome 9, is linked with ABO blood phenotype (20 cM apart)