Question

3. In E. coli translation of genes that contain a frameshift mutation often result in a truncated protein. This is because the frameshift mutation often result in a nonsense codon downstream in the DNA sequence. Can you come up with a reason why nonsense mutations are so prevalent after a shift in reading frame in an E. coli DNA sequence? (1 marks)

Answer 1

Ans) Nonsense mutations are so prevalent after a shift in reading frame in an E. coli sequene because When the reading frame is shifted, incorrect amino acids are encoded followed by frameshift mutation produces nonsense codons such as ‘TAG’ are usually produced.

• Since shift in reading frame cause alterations in the Amino acids followed by nonsense mutation brings about the changes in base pair arrangement this change is more prevalent,,,
• because frame shift reading frame has already mutated Amino acids along side base pair alteration together cause much impairment in Genes.
• When nonsense mutations occur there is a replacement of one base or a single nucleotide from another in the nucleotide sequence and ultimately brings changes in the complementary base of E.coli.
• Restoration of the wild-type DNA sequence requires loss of the extra ‘T,’ a ‘−1’ frameshift mutation. Pseudorevertants may be produced if another nearby nucleotide is lost. Loss of the bold ‘A’ in Figure 3 restores the reading frame and function will also be restored if phenylalanine can substitute in place of tyrosine.
• Shift in reading frame of E.coli brings changes in the the number of nucleotides due to either insertions or deletions of the nucleotides followed by structure of a gene changes because of nonsense mutation substitutions with another base pair.

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