A sequence in chromosomal DNA is the linear repetition of four base elements: Adenine, Thymine, Guanine and Cytosine in this molecule. Mutation is a stable heritable change in the sequence of nuclitides in the DNA. It is a change in the character of a gene that is perpetuated in subsequent divisions of the cell in which it occurs. The existence of mutation implies that the sequence of DNA in the living things is sufficiently stable than most individuals possess the same sequence. But sufficiently unstable that alterations do exist and can be found. The accumulation of significant mutations has the potential to increase your the genetic diversity of a specie. Such genetic diversity is an essential component of evolution and the ability of a specie to survive in changing environments.
Mutation occurs spontaneously at low frequency with or without an obvious external cause as a result of errors in replication and repair. They my be harmful especially if the affected area or sequence of nucleotide encodes a vital product of function or beneficial example those that increase the cells resistance to antibiotics.
Types of Mutation
Mutation occurs in various ways and they can have various effects on the genetic message. Often a piece of DNA is lost, gained, inverted or even transposed. These processes gives rise to different types of mutations.
- Point mutation : This involves a single nucleotide. It may consist of a loss of your nucleotide, by substitutionof one nucleotide of another or the insertion of additional nucleotide. For example if we consider genes as letters of the alphabet and chromosomes as sentences, a point mutation is like changing a letter in one word. Where this change consist of replacing of one nucleotide by another. It is known as base substitution
- Transposition mutation: This is the transfer of a small piece of DNA or a copy of it from one site to another the same duplex. The small specialized piece of DNA is called a Transposable element or jumping genes.
- Transition mutation : This is a point mutation involving substitution of one base pair for another that is replacement of one purine for another and one pyrimidines for another without changing the purine-pyrimidine orientation. Transition mutations are common but are often repaired by various proof reading functions such as the DNA polymerase an enzyme.
- Trqnsversion mutation : This is a point mutation involving base substitution in which the orientation of purine and pyrimidine is reversed. In contrast distinction to transition mutation that is purine is substituted for a pyrimidine.
Other mutations are frame -shift mutation, spontaneous -induced mutation, missense mutation, nonsense mutation and suppressor mutation.
All these change can cause morphological, physiological effects in an organism especially man. The mist common type of mutation is Cancer. And it’s dangerous because it gets incorporated in the genes which aids it to be passed from one generation to another.