4. In cats, having a white coat with colored patches is caused by the dominant a

Question

4. In cats, having a white coat with colored patches is caused by the dominant allele S, and individuals homozygous for the recessive allele s have solid coats. Short hair is caused by the dominant allele L, and individuals homozygous for the recessive allele / have long hair. A long-haired queen (female cat) with patches whose mother had a short solid coat mates with a short-haired, solid-coated tom (male cat) whose mother was long-haired and solid-colored. (5 each, 15 total) a. What are the genotypes of the mating pair? b. What kinds of kittens can arise from this mating and in what proportions? c. What kind of cat would you need to testcross the kittens?

Explanation / Answer

White coatwith colored patches: SS or Ss

Solid coats: ss

Short hair : LL or Ll

long hair: ll

a ) Long haired female with patches: SSll or Ssll

short haired solid coat male: ssLL or ssLl

Therefore, the genotypes of parents are SSll and ssLL

b)

SS x ss: Ss and Ss Colored patches

ll x LL: Ll and Ll short hair.

SSLL

patches, short hair

SSLl

patches, short hair

SsLL

patches, short hair

SsLl

patches, short hair

SSLl

patches, short hair

SSll

patches, long hair

SsLl

patches, short hair

SSll

patches, long hair

SsLL

patches, short hair

SsLl

patches, short hair

ssLL

solid, short hair

ssLl

solid, short hair

SsLl

patches, short hair

Ssll

patches, long hair

ssLl

solid, short hair

ssll

solid and long hair

The kittens of 4 genotypes are produced. These are patches short hair with genotypes SSLL, SsLL, SSLl and SsLl.

Patches long hair: SSll or Ssll

Solid and short hair : ssLL or ssLl

solid and long hair" ssll

The genotypes of kittens are in 9:3:3:1 ratios.

c) The test cross is carried out between a homozygous recessive cat for both traits, solid coat and long hair (ssll) and kittens with any genotype.

male/ female SL Sl sL sl SL

SSLL

patches, short hair

SSLl

patches, short hair

SsLL

patches, short hair

SsLl

patches, short hair

Sl

SSLl

patches, short hair

SSll

patches, long hair

SsLl

patches, short hair

SSll

patches, long hair

sL

SsLL

patches, short hair

SsLl

patches, short hair

ssLL

solid, short hair

ssLl

solid, short hair

sl

SsLl

patches, short hair

Ssll

patches, long hair

ssLl

solid, short hair

ssll

solid and long hair

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