Which of the following explains the mutagenic effect of nucleoside analogs? 1) T

Question

Which of the following explains the mutagenic effect of nucleoside analogs?

1) They break covalent bonds in the DNA sugar-phosphate backbone, which can cause physical breaks in chromosomes.

2) They cause adjacent thymine bases in a DNA strand to cross-link, which leads to problems in DNA replication and transcription.

3) They can be incorporated into DNA strands, slipping between stacked base pairs, which leads to insertions or deletions in DNA replication.

4) They can be incorporated into DNA in place of normal bases, but in DNA replication, they cause mistakes in base-pairing.

Explanation / Answer

The nucleosides that have a nucleic acid analogue, a sugar and 1-3 phosphate groups is known as Nucleoside analogues. These nucleotide analogues used as therapeutic drugs for the prevention of viral replication in viral infected cells. The agents such as acyclovir (one of the nucleotide analogue) can be used against many viral infections. They are act as antimetabolites after phosphorylation and after phosphorylation they can incorporate into the DNA strand during replication because they have structural similarity with the nucleotides. These nucleotide analogues prevent viral DNA polymerase to move and stops replication because the functions as chain terminators.

Hence, the write option is- 4). They can be incorporated into DNA in place of normal bases, but in DNA replication, they cause mistakes in base-pairing.

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