Question

What is the effect of deletion mutation?

Answer 1

Mutations are sudden changes in genotype, involving qualitative and quantitative alterations in the genetic material itself which change the phenotype of an organism. Mutation may occur at any stage in the development of organism, it may take place either in somatic cells or in the germinal tissue (sex cells), it may arise spontaneously in nature or may be induced artificially,it may be harmful or useful.

Complete answer:
Mutations are of two types:
1. Chromosomal mutations (chromosomal aberration):
May result in alteration in the amount or position of genetic material.
2. Gene Mutation (point mutations):
They are permanent heritable changes in genes or Castroneves of the DNA molecule i.e. alterations in the chemical structure of gene at molecular level.

Deletion mutation: This comes under chromosomal mutations in which a small segment of the chromosome is lost completely(some genes are lost). This loss of a segment may be terminal or intercalary depending upon its occurrence at the tips or between the two ends of the chromosomes.

The terminal deficiencies are rare and first observed by Barba McClintock in corn.
In intercalary or interstitial deficiency, a chromosome is broken into three segments (double break), the two terminal segments rejoin and the separated segment is lost.
In human beings the effect of loss of portion of chromosome number 5 was described by Lejeune(1963). The affected infant utters feeble cries resembling the meeting of a cat. This condition is also referred to as Cri du chat syndrome.
A deletion mutation can remove a single nucleotide or entire sequences of nucleotides. If three or more nucleotides are lost in a gene, entire amino acids can be missing from proteins created which can have serious functional effects.
Deletion of a number of pairs that are not evenly divisible by three will lead to a frameshift mutation, which causes all of the codons occurring after the deletion to be read incorrectly during translation, which produces a severely altered and potentially nonfunctional protein.

Note:
Mutations may affect the structure and functioning of an organism, mutations are usually recessive and very few mutations are dominant, but if they are dominant then they are usually lethal in their action but may be beneficial or at least not harmful. On the basis of their mode of occurrence mutations can be divided into two broad categories: spontaneous mutations and induced mutations.