The gene B for Brown Eyes is dominant and can be found in individuals with an al

Question

The gene B for Brown Eyes is dominant and can be found in individuals with an allele makeup of BB or Bb. Blue eyes are recessive genes and are mainfest on individuals with an allele makeup of bb. Assume independence. a. A blue eyed and brown eyed couple produce 3 offspring.

a) What is the probability that all three offspring have blue eyes? consider that the brown eyed parent has 1/3 chance of being BB. b. A blue eyed and brown eyed couple produce 1 offspring.

b) What is the probability that one parent was Bb, given that the baby has brown eyes? consider the brown eyed parent has a 1/3 chance of being BB.

Explanation / Answer

Gene B - Brown Eyes - found with allele makeup of BB or Bb

Blue Eyes - found with allele makeup of bb

A blue eye and brown eye couple produce 3 offspring,

a) Probability that all three offspring have blue eye = number of makeup found blue eyes / total number of makeup

= 1 / 3

= 0.3333

Probability that all three offspring have blue eye = 0.3333

b) By assuming independence,

Probability that one parent was Bb, given that the baby has brown eyes = Probability that one parent was Bb * Probability that  baby has brown eyes

=1/3 * 2 /3

= 0.2222

Probability that one parent was Bb, given that the baby has brown eyes = 0.2222

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