Mutation is any sudden genetic change either naturally or artificially takes place in an individual which bring about the sudden appearance and loss of some characters in an individual which can be inherited.
DNA is the information macromolecule which is the principal genetic material carries genes in terms of sequence of nucleotides. Point mutation carries genes in terms of sequence of nucleotides. Point mutation is the change in any fraction of DNA includes a very limited segment of DNA molecule at any point or involves few base pairs or alteration of one or more nucleotides.
Point mutation in broad sense is the mutation at molecular level or gene level. It includes following types:
Deletion:
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This is the point mutation which is caused due to loss or deletion of single nucleotide in a triplet codon of a gene, is called deletion mutation.
Insertion Mutation:
The point mutation which occur due to addition of one or more extra nucleotides to a gene are called insertion reactions.
This type of point mutation can induced in DNA by application of chemical mutagens. In this mutation the code word alters.
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Substitution Mutation:
The point mutation in which nitrogen base of triplet codon of one DNA is replaced by another base or some derivative of nitrogen base are called substation mutations.
This alters the phenotype an individual. This type is point mutation takes place by tautomerization, deamination and substitution of any base analogues.
Tautomeric shifts occur due to shifting of electrons or protons in the normal nitrogen bases to convert them in their rate states or tautomers. In this process amino group of Cytosine base tautomers and likewise in other bases. Thus pairing quality change. As a result of which cytosine can bond with Adenine. Thyamine can bond guanine instead of making normal pairing.