Recombination Frequency - Westford Academy Ap Bio

Report
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%
• 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
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:
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
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:
(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

similar documents