Question

Mutations due to small insertions and deletions can arise spontaneously during DNA replication due to:

A. A tautomeric shift taking place so that cytosine in the new DNA strand is able to pair with an adenine in the template strand.
B. A purine in the template DNA strand mispairing with an incoming pyrimidine.
C. A purine in the template DNA strand mispairing with an incoming purine.
D. Depurination of guanine.
E. Strand slippage.

Answer 1

Small insertions and deletions during DNA replication can be caused by strand slippage, where misalignment of DNA strands leads to mutations if not corrected.

Step-by-step explanation:

Mutations due to small insertions and deletions can arise spontaneously during DNA replication. One possible mechanism for this occurrence is strand slippage. This happens when the newly synthesized DNA strand slips backward or the template strand slips forward, leading to a misalignment of the DNA strands. As a result, nucleotide insertions or deletions can occur, which if not corrected by DNA repair mechanisms, can become permanent mutations. Other options mentioned, like tautomeric shift, purine and pyrimidine mispairing, depurination of guanine, and spontaneous deamination of cytosine, are also mechanisms by which mutations can occur, but they generally lead to different types of mutations like point mutations rather than insertions or deletions.