A somatic mutation, which is identified as a phenotypic change in a somatic cell which is consistently transmitted to the daughter cells arising through mitotic cell division, results from some permanent alteration in the nuclear, or chromosomal, DNA of the parent cell. Two types of mutation have been generally identified although the distinction between the two types has often been vague and based purely on pragmatic considerations. The two types of mutation commonly discussed are the “point” or “gene” mutation and the “chromosomal” mutation. The “point” or “gene” mutation is considered to be associated with a small alteration in the DNA structure, such that the base sequences which code for a specific amino acid, and form part of a single gene, are altered. The “point” mutation is thus revealed in an alteration of one specific gene with no concomittant alterations in any other genes. The “chromosomal” mutation is a much more far-reaching alteration in the genome of the cell, involves simultaneously several different genes and is supposedly associated with a rearrangement of the chromosomal material or with the complete loss of part of a chromosome from the cell.
KeywordsSomatic Mutation Double Strand Break Mutation Frequency Gene Conversion Specific Mutation
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