Question

An asynchronous culture is given 3H-thymidine for a period of time, usually about 30 minutes. During the labeling period, 42% of the cells incorporate radiolabel. At numerous times after the exposure, samples of the cells were collected and autoradiograms were prepared. The first radiolabeled mitotic figures appeared in the sample that was collected six hours after the 3H-thymidine radiolabel was first presented to the cells. The autoradiograms were stored for 75 hours before they were developed. How long is the G2 phase

Answer 1

Answer:

How long is the G2 phase = 6hours

Explanation:

Cell cycle undergoes various stages  during mitotic cell division.

Normally cells are arrested in the resting phase G0 but as the cell division starts it undergoes G1 the growth phase then it undergoes S phase called the Synthesis phase in which the DNA synthesis occurs. Then it undergoes G2 Phase and is the shortest phase while G1 is the longest phase of the cycle. G2 normally lasts for 3-4 hours so here it may take 2.775 hours as due to presence of Thymidine the synthesis of DNA occur at high level so it contains higher levels of cellular DNA than in the G1 . so it will take  6hours G2 phase to occur.