Analysis ll: DNA repair experiments 1. a) Stu dents who exposed Rad1 mutant yeas

Question

Analysis ll: DNA repair experiments 1. a) Stu dents who exposed Rad1 mutant yeast on YEPD plates to UV light got the following results Provide an explanation for these results. (2 marks) What conclusions can be drawn from this? UV dose (t secs) Wildtype yeast Rad1 mutants 352 2347 339 220 310 10 20 105 b) The wildtype yeast have a high proportion of survivors at 2 and 5 seconds. Is this due to the fact that these short doses are not long enough to cause DNA damage? Explain why or why not. (2 marks)

Explanation / Answer

1a.
The data suggests that Rad1 mutants are sensitive to UV exposure. WT yeast can tolerate exposure to UV and survive. But, a mere 2 sec UV exposure cause significant cell death in rad 1 mutant. This shows that Rad1 mutants are hypersensitive to DNA damage caused UV radiation as they lack proper DNA repair mechanisms.

1b.
Exposure of UV radiation for 2 sec or 5 sec is sufficient enough to cause cell death in rad1 mutants. It suggests that UV radiation exposure for this small time duration is sufficient enough to induce cell death. However, WT cells are resistant to cell death at this exposure indicating that they can manage the DNA damage and repair it.

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