Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?
A) G0
B) G1
C) S
D) G2
E) M

Question

Quizplus · Accepted Answer

The nucleus would contain 6 picograms of DNA in the G2 phase of the cell cycle. This is because during the S (synthesis) phase, the DNA content doubles as the DNA is replicated. If the normal (G1) amount is 3 picograms, then after replication in the S phase, the amount would be 6 picograms, which is the amount observed before the cell enters mitosis (M phase). The G2 phase follows the S phase and precedes the M phase, where the cell prepares for division with twice the DNA content of the G1 phase.

Measurements of the Amount of DNA Per Nucleus Were Taken