Question

Which of the following mutations would be most likely to have a harmful effect on an organism?

• A. A single base insertion near the start of the coding sequence
• B. A base-pair substitution
• C. A single base deletion near the middle of an intron
• D. A single base deletion close to the end of the coding sequence

Answer 1

The correct option is A A single base insertion near the start of the coding sequence

A single base insertion near the start of the coding sequence will cause a frameshift mutation. Due to the triplet nature of gene expression by codons, the insertion will change the reading frame, resulting in a completely different translation from the original. Hence, this will cause the most likely harmful effect.

So, the correct option is 'A single base insertion near the start of the coding sequence'.