qq2 - 2confused2bdoctor

[ArchivalUser]

An actively replicating cancer cell line with fluorescently labeled DNA is passed through a cell sorter and divided into three pools. Fifty percent of the cells contain a DNA content of N, 20% contain 2N, and the remaining 30% has varying amounts of DNA between N and 2N. Assuming that the life cycle of this cell line is approximately 20 hours, about how much time do the cells spend in S-phase on average?
A. 2 hours
B. 4 hours
C. 6 hours
D. 10 hours
E. 20 hours

[ArchivalUser]

CCC. S phase has DNA between N and 2N, 20h*30%=6h. just run flow cytometry today.

[ArchivalUser]

ccc

[ArchivalUser]

The correct answer is C. The DNA content of the cells should be N during G1 or G0, 2N during G2 and M, and anywhere between N and 2N during S-phase, when DNA synthesis is actively occurring. Therefore, 30% of the cells are undergoing S-phase at any time. And because the life cycle of this cell line is 20 hours, 30% of 20 hours is equal to 6 hours.