Question

If a single base in the middle of a protein coding open reading frame is replaced with another base, which statement from the following is NOT a likely possibility?

• A. It may not make any difference to the protein sequence.
• B. It may cause a single amino acid mutation.
• C. It may create a premature stop codon.
• D. The mRNA will not be recruited for translation.

Hint:

Most single base substitutions in the coding region affect only the protein product, not the mRNA’s ability to be translated.

Answer 1

The Correct Option is D

Step 1: Understand base substitutions.
A point mutation or single base change in the coding region of a gene can have several effects depending on where and how it occurs.

Step 2: Analyze the possible outcomes.
It may be a silent mutation where the codon changes but the amino acid remains the same due to codon redundancy.
It may be a missense mutation where one amino acid is substituted for another.
It may also be a nonsense mutation where the codon is changed to a stop codon, resulting in premature termination.

Step 3: Evaluate the incorrect option.
Recruitment of mRNA for translation occurs via the 5’ cap and other regulatory elements outside the coding region. A base change in the coding region does not prevent mRNA from being translated. Hence, option (4) is not a likely consequence of such a mutation.