Snow leopards live in the high reaches of the Himalayas and have several adaptations to deal with living most of the time in snow. They have wide paws with hair between the toes to allow them to run on top of the snow crust. Assume that wide paws (W) and hair between the toes (T) are both dominant traits and are on the same chromosome. Suppose that two snow leopards, heterozygous for both traits, mate. Suppose further that in the female, the two dominant alleles are on the same chromosome of the homologous pair, while in the male, each chromosome of the pair has one dominant and one recessive allele.

1) What percentage of each of the following genotypes will be produced?

WWTT:

WWTt:
WWtt:

WwTT:
WwTt:
Wwtt:
wwTT:
wwTt:
wwtt

2) How many of the offspring (assume 4 cubs) will have narrow paws with hair between the toes?

Answer:

1) Percentage of each of the following genotypes

WWTT: 0
WWTt: 1/4 = 25%
WWtt: 0
WwTT: 1/4 = 25%
WwTt: 0
Wwtt: 1/4 = 25%
wwTT: 0
wwTt:1/4 = 25%
wwtt: 0

2) Offspring with narrow pows: 1 of four individuals.

Explanation:

Available data:

wide paws (W) and hair between the toes (T) are both dominant traits
narrow paws (ww) and no hair (tt) are bothe recessive traits
Both traits are on the same chromosome.
Female: W and T on the same chromosome of the homologous pair, w and t on the other chromosome.
Male: W and t on the same chromosome of the homologous pair, w and T on the other chromosome.

Cross: Between two heterozygous individuals

Parental) WwTt x WwTt

Sex) Female Male

Gametes) WT wt Wt wT

Punnett square)

WT wt

Wt WWTt Wwtt

wT WwTT wwTt

F1) Genotypes:

1/4 WWTt
1/4 Wwtt

1/4 WwTT
1/4 wwTt

Phenotypes:

2/4 = 1/2 = 50% wide paws with hair (W-T-)
1/4 = 25% wide paws with no hair (W-tt)
1/4 = 25% narrow paws with hair (wwT-)

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3 years ago