Why are we using more dilute cultures for the killing curve while we are using the arg selection culture at full strength?
1. The reason that we are using a more dilute culture for the killing curve is because we want to know how UV light exposure at different time intervals effects that growth of yeast, however, the arg selection culture has to be at full strength because that is our control variable and we want an equal possible situation for yeast to be grow.
2.How would you find the arg+ mutants on the killing curve plates?
2. The way to find arg+ mutants on the killing curve plates is after each plate is exposed to their respective amount of time under the UV light we will count the number of mutations that grew on the plate and we will know which plate is viable for mutations to go from an arg- to arg+.
5.Why do we have to incubate the plates in the dark?
6. The reason that the plates have to be placed in a dark location after being exposed to the UV light is to prevent mutations happening to the colonies inside the plates. The formation of pyrimidine dimmers, the major type of damage caused by UV light, distorts the double helix and blocks transcription or replication past the damaged site. Direct reversal of DNA damage is one repair mechanism used to restore damaged DNA. This is the most energy efficient method.
6. How does our experimental design allow us to determine that the UV caused the reversion from arg- to arg+ and not simple spontaneous suppressor mutations?
7. The experimental design allows us to determine that the mutation arg- to arg+ is due to a revertant mutation. This is due because we are exposing the culture to UV light and this initiates the repair mechanisms to react and fix the DNA sequence to these colonies, we now if or if not this mechanism worked due to the number of colonies grown on the plate after a week
Exposure to UV light causes pyrimidine dimer formation. The pyrimidine dimer can be repaired by direct reversal and NER. It can also be bypassed by activation of the SOS response.
a. Which of these three pathways maintains the arginine auxotrophy? Why?
NER
b. Which of these three pathways changes the arginine auxotrophy to prototrophy? Why?
SOS
2 answers