Part B: Appled Queshions ou Creaie a Strain of ueast that hda No mutations: a mu
ID: 194010 • Letter: P
Question
Part B: Appled Queshions ou Creaie a Strain of ueast that hda No mutations: a mutaioh in a his and a mutation in a me met-1) Thesc Cannot mrake rer owin hisidinre or rON up a Cuture of thp double muont for growith methionine both recessan to of OF of mret- 3 x 10 Frequanay of Induced rersion Ofhi at 20sec WSuvivors (PT) Por portion 5x 10-5 0-38 0) You Plate O Iml rom the 101 dilutiona onto ach of the Following Plates. How colonies do predict on each pate if cels are rot exposed to UV light You must Netnioninc bI You then Platc O Iml from 10 diution onto YEDP Platcs and expose the cels to 20 OF uv ight ro colonies co uou exped? How manExplanation / Answer
Answer a.
Reversion frequency of Met-1 mutants [spontaneous reversion] = No. of revertants / No. of mutants
or No of revertants = Reversion frequency of Met-1 mutants [spontaneous] x No. of mutants
= 5 x 10-6 x 32 x 109
= 160 x 103
= 1.6 x 105 cells/ml
Since the proprtion of survivors is 0.38 or 38%, so
Total No. of revertants = 0.38 x 1.6 x 105
= 0.608 x 105
= 60,800 cells/ml
Similarly No. of Met -1 revertants [UV-induced] = 3.9 x 108 cells
Number of Met-1 revertants [spontaneous as well as induced] = 3.9 x 108 + 6.08 x 104
= 390060800 cells
= 3.9 x 109
Now, this cells are diluted to 1/10th of their conc.
Hence number of cells plated = 3.9 x 108 / ml
As 0.1 ml of this dilution is plated, the no. of cells will be = 3.9 x 107. Assuming each cell forms a single colony,. Therefore, we will get these number of cells on YM + His medium.
Same way calculations can be done for YM+ Meth medium.
On YM containing Meth and Hist, the aboce two have to be added.
As far as YM minimal medium is concerned, no colonies are expected.