Question

What are the causes of mutation?

Answer 1

Mutation can be defined as a process that involves sudden changes in gene sequence of a DNA. It is a kind of mistake committed by genes while crossing over therefore, it sometimes takes place at the time of cell division.

Complete Answer
In order to understand the causes of mutation, we need to understand the complete process of cell division and gene exchange as they play a vital role in mutation.
The complete process of cell division can be described in following steps:
-Meiotic cell division takes place within the body of an organism.
-Homologous chromosomes (chromosomes of the same kind coming one from each parent in the diploid cell) come together to proceed with the process of crossing over.
-Crossing over is the process in which homologous chromosomes form Chiasma (site of gene exchange on overlapping bodies of homologous chromosomes) for genetic recombination.
-Sometimes, due to some reasons these steps are disrupted by sudden change in one or more genes or in the number of chromosomes or in the structure of chromosomes.
We can understand this process better with the help of the following example:
Say, a man called Suresh, having 46 chromosomes has his unique genetic identity. By virtue of the normal cell division process, his son also has 46 chromosomes. However, Suresh’s third generation, comes out to be a special child with 46.1 chromosomes. This sudden change in the number of chromosomes invokes growth of the sixth finger in one of his hands. This unusual growth of finger is a result of mutation and this process of sudden alteration in genes is called mutation. Now this can be possibly due to following reasons:
-Improper transmission or copying of genes within a cell at the time of division: This is one of the most reliable reasons given by the scientists for mutation. Therefore, one can say that improper genetic coding can probably lead to mutation.
-Over-exposure to harmful radiations: This is another reliable reason for mutation. Exposure to radiation, chemicals, pollution can cause mutation in genes. They are capable enough to alter the genes.

Note:
Genetic disorders besides inherited can also arise due to abnormality of genetic coding or sudden mutations in DNA. Such a change is absolutely resistant to cure or treatment processes except for the gene therapy.