Question

3 Did the E coll grow on the unexposed side of the TSA plate (in other words, the side of the plate placed over the edge of the transilluminator)? 4 Did the E. coli grow on the UV exposed side of the TSA plate? Explain your results. 5 Was there a difference in the amount of growth of the E. coli after 105, 205, 40s and Bos of UV exposure? Explain your results. 6 Why was there still E. coli growth after UV exposure? How can you explain this result? The UV exposer can cause a thymine dino in the cell that can be lethal for cell and the cell dies. But if it survives it candosoby photo reactivation of dark reactivation. 7 Did any colonies D.radiodurans grow on the unexposed side of the TSA plate? Explain.

Answer 1

1. Yes, colonies of E. Coli grow on the unexposed side of TSA plate.
2. Very few colonies of E, coli grew on UV exposed side of the plate. The no. Of colonies was much smaller that what observed in non exposed side of the plate. It appears that UV rays inhibited the growth of cells.
3. Yes, more the UV exposure less was the growth of E.coli. The 10s and 20 s exposure produced more colonies compared to 40 and 80s exposed samples.
4. UV exposure killed many cells, but one who survived where able to rapid the Thymine dimer caused by UV rays. The enzymes UvrA,B,D can repair the DNA damage. Photo reactivation can also help remove the Thymine dimer.
5. Yes, D, radiodurans colonies were observed on the unexposed side of TSA plate.