(N/A) Mutation is defined as a sudden inheritable change in the genetic material.
It is categorized into the following types:
$(i)$ Point mutation: This involves a change in a single base pair where one base is replaced by another. $A$ classical example is the change of a single base pair in the gene for the $\beta$-globin chain,which results in the substitution of the amino acid glutamate with valine. This leads to a condition known as sickle cell anemia.
$(ii)$ Frameshift mutation: This is a change in the reading frame of the genetic code due to the insertion or deletion of base pairs.
$(a)$ Insertion: If one or more nucleotides are added to the $DNA$ segment,it is called insertion. If three or a multiple of three bases are added,the reading frame remains unchanged,but a protein with additional amino acids is formed.
$(b)$ Deletion: If one or more nucleotides are removed from the $DNA$ segment,it is called deletion. Similarly,if three or a multiple of three bases are removed,one or more amino acids are deleted from the polypeptide chain.