Problem:

You expose synchronized tissue culture cells to radioactive thymine throughout S phase (pulse), then wash this material off (chase), and apply autoradiography to the metaphase chromosomes at the subsequent metaphase.

Question 1: How would the radioactivity be distributed in the in the sister chromatids of each mitotic dyad.

Question 2: How would the radioactivity be distributed in the sister chromatids of each mitotic dyad if the pulse-labelled cells from part a are allowed to progress to a second mitosis? Would you expect to see differences from one cell to another?

Question 3: How would the radioactivity be distributed in the sister chromatids of each dyad if the cells are allowed to progress to a third mitosis? Would you expect to see differences from one cell to another? Illustrate your answers with the generic chromosome, indicating which of the chromatids is radioactive and which is not. Assume there is no mitotic recombination.

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