Recombination Frequency and Gene Linkage Mapping

Linked vs. Unlinked Genes

Crossing Over

Crossover Frequency

Mapping Using Frequency

Mapping Gene Loci

Recombination frequency (Recombinant offspring) (Total offspring)

A wild-type fruit fly (heterozygous for gray body color and normal wings) was mated with a black fly with vestigial wings. The offspring has the following phenotypic distribution: Wild type 778 Black-vestigial 785 Black normal 158 Gray vestigial 162 What is the recombination frequency between these genes for body color and wing type?

A wild-type fruit fly (heterozygous for gray body color and normal wings) was mated with a black fly with vestigial wings. The offspring has the following phenotypic distribution: Wild type 778 Black-vestigial 785 Black normal 158 Gray vestigial 162 What is the recombination frequency between these genes for body color and wing type? (158+162) / (778+785+158+162) 320/1873 0.171 = 17.1%

produces the dihybrid - BbYy Black with white fat In rabbits the dominant allele B produces a black coat color and the recessive genotype bb produces a brown coat. Body fat color in rabbits is white if a dominant allele Y is present and yellow if the genotype is yy. Assume the mating between rabbits with the following genotypes : Black with white fat – BBYY Brown with yellow fat - bbyy produces the dihybrid - BbYy Black with white fat Calculate the recombination frequency if the dihybrids are mated back to brown rabbits having yellow fat, bbyy, and the following ratio of phenotypes is observed: BlackWhite125 BlackYellow75 BrownWhite85 BrownYellow115

produces the dihybrid - BbYy In rabbits the dominant allele B produces a black coat color and the recessive genotype bb produces a brown coat. Body fat color in rabbits is white if a dominant allele Y is present and yellow if the genotype is yy. Assume the mating between rabbits with the following genotypes : Black with white fat - BBYY Brown with yellow fat - bbyy produces the dihybrid - BbYy Calculate the recombination frequency if the dihybrids are mated back to brown rabbits having yellow fat, bbyy, and the following ratio of phenotypes is observed: BlackWhite125 BlackYellow75 BrownWhite85 BrownYellow115 (75+85) / (125+115+75+85) 160/400 0.40 = 40%

Question #1 In rabbits, black (B) is dominant to brown (b), while full color (F) is dominant to chinchilla (f). The genes controlling these traits are linked. The following cross was made: rabbits heterozygous for both traits that express black, full color, (BbFf) with rabbits that are brown, chinchilla (bbff). The following results were obtained: 31 brown, chinchilla (bbff) 35 black, full (B-F-) 16 brown, full 19 black, chinchilla Determine the map distance between the 2 genes.

Question #1 In rabbits, black (B) is dominant to brown (b), while full color (F) is dominant to chinchilla (f). The genes controlling these traits are linked. The following cross was made: rabbits heterozygous for both traits that express black, full color, with rabbits that are brown, chinchilla. The following results were obtained: 31 brown, chinchilla 35 black, full 16 brown, full 19 black, chinchilla map distance between the 2 genes (16+19) / (31+35+16+19) 35/101 0.35 = 35% 35 map units

Determine the sequence of genes along a chromosome based on the following recombination frequencies: b – vg 17 cn-vg 8 b-cn 9

Determine the sequence of genes along a chromosome based on the following recombination frequencies: b – vg 17 cn-vg 8 b-cn 9

Determine the sequence of genes along a chromosome based on the following recombination frequencies: b – vg 17 cn-vg 8 b-cn 9

Determine the sequence of genes along a chromosome based on the following recombination frequencies: A-B 8 A-C 28 A-D 25 B-C 20 B-D 33

Determine the sequence of genes along a chromosome based on the following recombination frequencies: A-B 8 A-C 28 A-D 25 B-C 20 B-D 33