Tetrad analysis shows that crossing-over occurs at the four-strand stage (i.e. , after replication)because, when two genes are linked,
A)NPD T.
B)T NPD.
C)T PD.
D)PD NPD.
E)PD T.

Question

Tetrad analysis shows that crossing-over occurs at the four-strand stage (i.e. , after replication)because, when two genes are linked,
A)NPD > T.
B)T > NPD.
C)T > PD.
D)PD > NPD.
E)PD > T.

Quizplus · Accepted Answer

T (tetratype) > NPD (non-parental ditype) indicates crossing-over between linked genes, as tetratypes result from single crossover events between two genes, showing that recombination occurs after DNA replication in the four-strand stage.

Tetrad Analysis Shows That Crossing-Over Occurs at the Four-Strand Stage