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Q4. For each of the following mutations in the 5 UTR of the trp operon, explain

ID: 273831 • Letter: Q

Question

Q4. For each of the following mutations in the 5 UTR of the trp operon, explain the effect on expression of the trp operon relative to wildtype (increased, decreased, or unchanged): Assume intermediate levels of tryptophan. (TrpR (repressor) is inactive.) a) Deletion of the entire 5' UTR sequence b) Deletion of DNA that would normally be transcribed to give the polyU sequence c) Mutation in region 4 such that it cannot bind with region 3 d) Mutation in region 3 such that it can bind with neither region 2 nor region 4 e) Mutation in region 2 such that it cannot bind with region 3 f) The two tryptophan codons in the 5 UTR are changed to glycine codons

Explanation / Answer

a) There will be increase/decrease in gene expression depend on mutation.

b) There is no formation of poly u sequence at 3' end. So that post transcription modification will defect and translation will be misleaded.

C) There is no formation of attenuator sequence.

d) If sequence 3 bind with sequence 2 there is no formation of attenuator and there will be no attenuation of transcription.

e) sequence 2 shouldn't bind with sequence 3. If it binds, there is no formation of attenuator. If mutation occurs in sequence 2 then attenuator forms easily.

f) protein expression will be wrong.