Question

Question 9 1 pts You are given a flask with standard liquid media containing a population of S. pombe cells that have a temperature sensitive mutation of a gene that causes complete loss of function of the gene product at the restrictive temperature. The flask had been incubating at the permissive temperature in the dark before it was given to you, and the cells in the flask were replicating asynchronously with respect to the stage of the cell cycle. The mutated gene in this strain of yeast encodes an essential component of a UV- mediated DNA damage checkpoint. Which FACS plot (see attached figure) best represents how cells in this flask would appear following growth for 30 min at the restrictive temperature ? (Note, assume that FACS plot #1 shows analysis of a population of S. pombe replicating asynchronously i.e. each cell within a population is at a random stage of the cell cycle) in culture. In the rich media assume the yeast have a cell cycle time of 100 min, with G1=50 min; S = 25 min; G2 = 15 min and M = 10 min). #2 #3 #4 #5 #6 cells in Grand 1 2 relative amount of DNA percell bitrary #2 #3 #4 #5 #6

Answer 1

Question 10.

The correct answer is #3

This is because S.pombe have been transferred into minimal liquid media containing no mitogens but having enough essential amino acids and glucose for survival. As mitogens are the those peptides which initiates the cell to undergo mitosis hence if it is not present than the cell will undergo G1 and S phase but not M phase.