A mutation occurs in a germ cell of a pure-breeding,wild-type male mouse prior to DNA replication.The mutation is not corrected,and the cell undergoes DNA replication and a normal meiosis producing four gametes.How many of these gametes will carry the mutation?
A)1
B)2
C)3
D)4
E)It is impossible to predict.

Question

Quizplus · Accepted Answer

Since the mutation occurs in a germ cell before DNA replication, both copies of the DNA strand in that cell will incorporate the mutation during replication. Consequently, after meiosis, which produces four gametes from each germ cell, each of the resulting gametes will carry a copy of the mutated gene. Therefore, 2 out of the 4 gametes will carry the mutation.

A Mutation Occurs in a Germ Cell of a Pure-Breeding,wild-Type