A particular cell type spends 4 hours in G1 phase, 2 hours in S phase, 2 hours in G2 phase, and 30 minutes in M phase. If a pulse–chase experiment were performed with radioactive thymidine on an asynchronous culture of such cells, what percentage of mitotic cells would be radiolabeled 9 hours after the pulse? a. 0 percent b. 50 percent c. 75 percent d. 100 percent

Video transcript

Hi everyone. Let's look at our next question. It says Assume that the total duration of the cell cycle in a typical human cell is 24 hours of which the G. One phase lasts about 11 hours. The G. Two phase about four hours. And the M. Phase about one hour. What will be the approximate duration of the S. Phase in that cell? Well we'll just put up our cell cycle diagram just to help us keep this keep track of all this. And I'm just gonna note on each of the parts of this um the times that were given. So we have the G. One phase lasting about 11 hours. We have the G. two phase about four hours On there and the M. Phase about one hour. So we've got four parts of the cell cycle. We've got time durations for three of them. And our problem also gives us the total duration of 24 hours. So we look at our answer choices, I notice that choice. This is insufficient data for interpretation but that's not going to be correct because we do have enough data to get this answer. So we need to know the length of the S. Phase. So we know that our total cell cycle is 24 hours. So we're just going to subtract four hours for G. Two one hour for m. and 11 hours for G. one. Which will end up subtracting a total of 16 hours for those three parts and that's going to leave us a total of eight hours for our S. Phase. So let's look at our answer choices and we can see that choice C. Is eight hours, so that's going to be our answer, and we can eliminate A and B as not being correct here. So again, um with a total duration of 24 hours and are given length of time for G two M and G one phases. We can calculate the approximate duration of the S. Phase in that cell is choice C. Eight hours. See you in the next video.