The father of Mr. Spock, first officer of the starship Enterprise, came from the

Question

The father of Mr. Spock, first officer of the starship Enterprise, came from the planet Vulcan; his mother came from planet Earth. A Vulcan has pointed ears (+), adrenals absent (+), and a right-sided heart (+). All of these alleles are dominant over Earth alleles. These genes are autosomal, and they are linked as shown in the linkage map: (1.0pts)

+/P                +/A                    +/R

|                      |                     |

      18 m.u.                16 m.u.

If Mr. Spock marries an Earth woman, what proportion of their children:

A. Will show Vulcan appearance for all three characters?

B. Will show Earth appearance for all three characters?

C. Will have Vulcan ears and heart but Earth adrenals?

D. Will have Vulcan ears but Earth heart and adrenals?

Pointed ears (P), adrenals absent (A), and a right-sided heart (R).

Explanation / Answer

All alleles are dominant over Earth alleles. But in the given case the father is heterozygous.

The genotype of mother is P/P, A/A, and R/R (mother) crossed with +/P, +/A, +/R

Vulcan appearance is parental type.

Here, genes are linked. 18mu distance between +/P. So, 82% progeny are parental type. 41% are +/P and 41% are P/P

Recombinants:- 9% will be +/P and 9% will be P/P.

Similarly talking about adrenals, 42% + 8% = 50% will have +/A and the rest 50% will have A/A

A. Proportion of offsprings that have Vulcan appearance for all three characters is 50% offsprings will show all three characters.

B. 50% will show earth appearance.

C. genotype is +/P +/R A/A= 1/8

D. Proportion of offsprings that have Vulcan ears but earth heart and adrenals is+/P A/A R/R = 1/8

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