LIFESCI 4 Lecture Notes - Lecture 13: Nonsense Mutation, Point Mutation, Intron
LIFESCI 4 - Lecture 13 - Mutations and Suppressors, Midterm Review
Nonsense mutations and nonsense suppressors
- Suppressor mutations are second mutations that reverse the effect of initial mutation
- Mut 1 RNA tyr Su-
- Amber mutation → the mutation on tRNA from [AUG] to [AUC] reverses the
effect of the point mutation
- Why are nonsense suppressor mutations not lethal?
- There are multiple copies of genes → even if one is mutated, the rest are
still functional
The genetic code and mutations
- (+1) site marks the start site of transcription
Effects of point mutations on protein activity
- Having a mutation in exons destroys the function since it is in the active site
- Having mutation in promoter may destroy the function by disrupting transcription
entirely
- Having mutation in other components may result in “neutral” → does not necessarily
destroy the function of the protein
- Having mutation in intron may destroy splice site, therefore destroy function of protein
Midterm Review
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Document Summary
Lifesci 4 - lecture 13 - mutations and suppressors, midterm review. Suppressor mutations are second mutations that reverse the effect of initial mutation. Amber mutation the mutation on trna from [aug] to [auc] reverses the effect of the point mutation. There are multiple copies of genes even if one is mutated, the rest are still functional. The genetic code and mutations (+1) site marks the start site of transcription. Having a mutation in exons destroys the function since it is in the active site. Having mutation in promoter may destroy the function by disrupting transcription entirely. Having mutation in other components may result in neutral does not necessarily destroy the function of the protein. Having mutation in intron may destroy splice site, therefore destroy function of protein. To kill f-: select for gal+ (kills least number of exconjugants while destroying f-) To kill hfr: select for lys+ (kills least number of exconjugants while destroying hfr)
