AAMC 8 Bio question

[iPodtosis]

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Last question on the bio section, it was a discrete question about a dividing cell treated with radio labeled 2-deoxythymidine for 30 mins, then washed away the excess unabsorbed radio labeled nucleotides, and then examine the cells and quantify the amount of incorporated 2-deoxythymidine. You are given a graph that shows the amt of 2-dT goes up and then come back down, then what stage is the cell at? I am conflicting between DNA synthesis and mitosis.

Hope whoever is reading this can understand my wording of the question 😛

 

[capn jazz]

please post all aamc questions in the thread for that aamc. you can find the links here: http://forums.studentdoctor.net/showthread.php?t=516243

anyway - it's from AAMC7, not 8. The answer is synthesis because in mitosis, during DNA synthesis, the radiolabeled T is taken up as the DNA replicates. Then it goes into mitosis, which takes the doubled DNA and halves it into 2 cells. So the % of the total cells that have the label remains constant because you're doubling the nuclei with the radiolabel but you're also doubling the total number of nuclei when the cell divides. (2*radiolabeled nuclei) / (2*number of nuclei before mitosis) = the same as before since the doubling term cancels.

The ACTUAL doubling happens during DNA synthesis. After a round of DNA synthesis, the amount of radiolabel increases. It's a really confusing question, but that's the best way I can explain it.

 

[iPodtosis]

thank you so much

 

[SuperSaiyan3]

anyway - it's from AAMC7, not 8.

I was about to say... I just did AAMC8 yesterday and I had no clue what you were talking about.

Capn jazz saves the day again.