#### Transcript Recombination Frequency - Westford Academy Ap Bio

```Recombination Frequency
and
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 – 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
• 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
(75+85) / (125+115+75+85)
– BlackYellow75
– BrownWhite85
– BrownYellow115
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
• 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:
o 31 brown, chinchilla (bbff)
o 35 black, full (B-F-)
o 16 brown, full
o 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
• 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:
(16+19) / (31+35+16+19)
o 31 brown, chinchilla
o 35 black, full
35/101
o 16 brown, full
0.35 = 35%
o 19 black, chinchilla
35 map units
• map distance between the 2 genes
• 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
```