Question

Define mutation. Illustrate the type of mutation that can arise by the change in chromosome structure.

Answer 1

A mutation is the change in DNA sequence. Mutations occur due to radiations like UV rays, or abnormal copying of DNA or disrupted cell division. Harmful mutation causes genetic abnormalities which are inheritable.

Complete answer:
To answer this question, we must know about the mutation and its types.
Mutations are the change in the DNA sequences which can alter the amino acid sequence. Any alteration in the amino acid can inactivate the protein function. This can lead to several serious cellular malfunctions.

Types of mutation which changes the structure are
i) Missense mutation-It occurs due to change in the single nucleotide base of an amino acid. It results in the alteration of amino acids which codes for different proteins.
ii) Insertion- It results in the addition of a few nucleotides in the DNA. It results in longer DNA sequence and the resultant protein may not function properly.
iii) Deletion - It results in the removal of a few nucleotides in the DNA. It results in a shorter DNA sequence. Larger deletions can result in deletion of the entire gene.
iv) Frameshift mutation-This mutation is the result of addition or deletion of bases which changes the gene’s reading frame. A reading frame has 3 bases for a particular amino acid. Addition or deletion may shift the reading frame.

Note: Mutation is the main reason for genetic variations. Most of the mutations are neutral. The mutations which are beneficial are selected through natural selection. The harmful mutations can lead to several diseases like sickle cell anaemia, cancer etc.