Identify the type of mutation, caused by single base pair.

The correct answer is Option (3) → Point mutation

A mutation is a change in the genetic material. A point mutation is a change of a single base pair in DNA. Sickle-cell anaemia is an example: one base change in the gene for the beta chain of haemoglobin (GAG to GUG in the mRNA) puts valine in place of glutamic acid.

(1) Frameshift mutation — Incorrect. This is caused by the deletion or insertion of base pairs. It shifts the reading frame of the codons, so it is not defined as a change of one base pair.

(2) Non-sense mutation — Incorrect. This is only one result of a point mutation, in which a codon changes into a stop codon. The general type that is defined by a single base-pair change is the point mutation.

(3) Point mutation — Correct. It is the change of one base pair.

(4) Silent mutation — Incorrect. This is also only one result of a point mutation, in which the changed codon still codes for the same amino acid. The general type is the point mutation.

NCERT Extract:
Chromosomal Disorders – …