The father of Mr. Spock is Vulcan; his mother is of terrestrial origin. A Vulcan has pointed ears (determined by the allele P), adrenals absent ( determined by A), and a right handed heart (determined by R). All are dominant to earth alleles. The three alleles are autosomal, and are linked as shown: P _____15 mu__________ A ________20 mu_______________R If Mr. Spock marries an earth woman, what portion of their children will be a) Vulcan phenotypes for all 3 characters? b) earth phenotypes for all 3 characters? c) Vulcan ears and heart but earth adrenals? d) Vulcan ears but earth heart and adrenals? Solution 50 % of the children will be Vulcan phenotupes. 50 % of the children will be of Earth phenotypes. When Spock (EeHh) marries and Earth woman and they may have a bunch of kids. If you do the Punnett square, you would predict that they would have: 1/4 with pointy ears and a left-sided heart 1/4 with pointy ears and a right-sided heart 1/4 with round ears and a left-sided heart 1/4 with round ears and a right-sided heart But, one more probablity is 1/2 pointy ears and right-sided heart and 1/2 round ears and left- sided heart. The likely reason for this is that these two genes are linked. So in Spock, his two genetic alleles are close together on the same chromosome (same one which he got from his Vulcan dad) and the rest two alleles were on his other chromsomes (the one which he received from his Earth mom). Now if Spock passes on chromsomes to his kids, they get mixed alleles from both the parents gene because the genes are so close together, crossing over cannot occur between the two genes. So Spock never passed on the different alleles combination. So it is quite possible why none of his children showed the mixed phenotypes..

1. The father of Mr. Spock is Vulcan; his mother is of terrestrial origin. A Vulcan has pointed ears
(determined by the allele P), adrenals absent ( determined by A), and a right handed heart
(determined by R). All are dominant to earth alleles. The three alleles are autosomal, and are
linked as shown: P _____15 mu__________ A ________20 mu_______________R If Mr.
Spock marries an earth woman, what portion of their children will be a) Vulcan phenotypes for
all 3 characters? b) earth phenotypes for all 3 characters? c) Vulcan ears and heart but earth
adrenals? d) Vulcan ears but earth heart and adrenals?
Solution
50 % of the children will be Vulcan phenotupes.
50 % of the children will be of Earth phenotypes.
When Spock (EeHh) marries and Earth woman and they may have a bunch of kids. If you do the
Punnett square, you would predict that they would have:
1/4 with pointy ears and a left-sided heart
1/4 with pointy ears and a right-sided heart
1/4 with round ears and a left-sided heart
1/4 with round ears and a right-sided heart
But, one more probablity is 1/2 pointy ears and right-sided heart and 1/2 round ears and left-
sided heart.
The likely reason for this is that these two genes are linked. So in Spock, his two genetic alleles
are close together on the same chromosome (same one which he got from his Vulcan dad) and
the rest two alleles were on his other chromsomes (the one which he received from his Earth
mom). Now if Spock passes on chromsomes to his kids, they get mixed alleles from both the
parents gene because the genes are so close together, crossing over cannot occur between the two
genes. So Spock never passed on the different alleles combination. So it is quite possible why
none of his children showed the mixed phenotypes.