Question

What would be the most likely effect on the transcription of the trp structural genes for the mutation scenarios provided? mutation that prevents ribosome binding to the mRNA 5' UTR mutation that changes region 1 tryptophan codons into alanine codons mutation that creates a stop codon in region 1 of mRNA 5' UTR deletions in region 2 of the mRNA 5' UTR deletions in region 3 of the mRNA 5' UTR deletions in region 4 of the mRNA 5' UTR deletion of the string of adenine after region 4 of the mRNA 5' UTR

Answer 1

Answer:

Explanation:

Trp structural genes are the genes that make up the trp operon. This operon encodes genes that leads to the production of enzymes that aids in the synthesis of tryptophan. the operon is made up of five structural gens, trp A, B, C, D, E. Attenuation is a mechanism that causes premature termination of transcription of the trp operon when tryptophan is abundant.

Mutation that prevents ribosome binding to the mRNA: Transcription of the trp structural genes will not occur. there will be no gene expression will occur.

5' UTR mutation that changes region 1 tryptophan codons into alanine codons: If alanine codons have replaced tryptophan codons, then under conditions of low alanine, the stalling of the ribosome will not occur. The attenuator will form, stopping transcription.

mutation that creates a stop codon in region 1 of mRNA: this will cause the ribosomes to stall there and transcription will not proceed because the attenuator can be formed.

5' UTR deletions in region 2 of the mRNA: If region 2 of the mRNA 5' UTR is deleted, the antiterminator cannot be formed thus allowing formation of the attenuator and transcription stops.

Deletions in region 3 of the mRNA 5'UTR : Attenuation will not occur, and transcription of the trp structural genes will proceed.

Deletions in region 4 of the mRNA 5'UTR : There will be no formation of the attenuator by the 5' UTR mRNA. Transcription will proceed.  

Deletion of the string of adenine nucleotides that follows region 4 in the 5'UTR: No termination will occur because for the attenuator to function as a terminator, it requires uracil nucleotides and not adenine following region 4 in the mRNA 5' UTR.  

Answer 2

Answer:

I've responded to each scenario individually, please see below:

1. mutation that prevents ribosome binding to the mRNA

No transcription occurs

2. 5' UTR mutation that changes region 1 tryptophan codons into alanine codons

Transcription when alanine is low

3. mutation that creates a stop codon in region 1 of mRNA 5' UTR

Transcription occurs, a truncated protein will be made during translation

4. deletions in region 2 of the mRNA 5' UTR

Transcription occurs, region 1 and 2 might get paired together

5. deletions in region 3 of the mRNA 5' UTR

Transcription occurs, region 3 and 4 could combine to form a hairpin loop structure

6. deletions in region 4 of the mRNA 5' UTR

Transcription occurs, region 3 and 4 could combine to form a hairpin loop structure

7. deletion of the string of adenine after region 4 of the mRNA 5' UTR

Transcription occurs, however, it will not be as stable a molecule because of losing its polyA tail

Hope that answers the question, have a great day!