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Suppose that to snow leopard’s, heterozygous for both traits meet. Suppose further that in the female, the two dominant alleles are on the same chromosome of the homologous pair, while in the mail, each chromosome of the pair has one dominant and one recessive allele. What is the expected phenotypic ratio of their children?

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marianaegarciaperedo

Complete question:

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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