I have three questions in mutations. 1. A mutation that makes the A-site of the
ID: 61653 • Letter: I
Question
I have three questions in mutations. 1. A mutation that makes the A-site of the ribosome about 40% less likely to bind to an amino-acyl tRNA 2. A mutation that changes a Threonine (Thr) tRNA anticodon from 3'UGC'5 to 3'UGG'5. 3. A mutation that allows sigma to bind more tightly to the promoter of the gene coding for initiation factor protein. (remember that initiation factor proteins help the small ribosomal subunit bind to an mRNA) For each number, Can you list how would the mutation affect? thank you.
Explanation / Answer
1. A mutation that makes the A-site of the ribosome about 40% less likely to bind to an amino-acyl tRNA.
When there is a mutation in the A-site of the ribosome, amino-acyl tRNA cannot bind to it properly, affecting the translation procsynthesis of peptide.
2. A mutation that changes a Threonine (Thr) tRNA anticodon from 3'UGC'5 to 3'UGG'5.
There would not be any affect due to this mutation, as both these codons code for the same amino acid serine.
3. A mutation that allows sigma to bind more tightly to the promoter of the gene coding for initiation factor protein.
As sigma factor is needed for the initiation of RNA synthesis (transcription), a tightly bound sigma factor will make the transcription process happen continuously. Thus, this mutation keeps the transcription process ‘on’ continuously and increases the rate of transcription.