recombination frequency and gene linkage mapping
TRANSCRIPT
Recombination Frequencyand
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%
• 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 – BBYYBrown 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
• 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 - BBYYBrown 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:
o31 brown, chinchilla (bbff)o35 black, full (B-F-)o16 brown, fullo19 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:
o31 brown, chinchillao35 black, fullo16 brown, full o19 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