Question

Which among the following types of point mutation is usually less harmful?

• A. Deletion
• B. Insertion
• C. Substitution
• D. Deletion and insertion equally

Answer 1

The correct option is C Substitution

Mutation is a sudden change in the DNA sequence that leads to an alteration in the basic structure of the gene sequence of the DNA, resulting in the formation of undesired proteins. Mutation can result from many ways like- DNA copying mistakes during cell division, exposure to mutagens and ionizing radiation, etc.
Mutation can lead to small scale changes or large scale changes. When gene mutation occurs due to change in a single base pair of DNA, it is known as point mutation. Three types of DNA mutations are base substitution, deletion and insertion.

In case of insertion of a single base pair, the whole frame of the sequence of the DNA gets shifted and all the downstream sequence gets altered, so it will create a condition of frameshift mutation and hence consequences can be more harmful.
In the case of single-base deletion, the whole DNA sequence downstream to the mutation will get altered affecting all the synthesized proteins leading to harmful consequences.

In the case of substitution mutation, one base is substituted by another nucleotide. In the resultant substitution, there could be a chance of a stop codon, or masking of a stop codon or changing a codon to synthesise a different amino acid. The whole DNA sequence downstream the mutation will not get affected by the mutation and hence the consequences can be assumed to be less severe as compared to the deletion and insertion.