point mutation

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Related to Base-pair substitution: point mutation

mutation

 [mu-ta´shun]
1. a permanent transmissible change in the genetic material.
2. an individual exhibiting such a change.
point mutation a mutation resulting from a change in a single base pair in the DNA molecule.
somatic mutation a genetic mutation occurring in a somatic cell, providing the basis for mosaicism.
suppressor mutation the correction of the effect of a mutation at one locus by a mutation at another locus.

point mu·ta·tion

a mutation that involves a single nucleotide; it may consist of loss of a nucleotide, substitution of one nucleotide for another, or the insertion of an additional nucleotide.

point mutation

n.
A mutation that changes one nucleotide in a gene or DNA sequence by substitution, deletion, or addition.

point mu·ta·tion

(poynt myū-tā'shŭn)
A mutation that involves a single nucleotide; it may consist of loss of a nucleotide, substitution of one nucleotide for another, or the insertion of an additional nucleotide.

point mutation

The replacement of one NUCLEOTIDE with another. This need not necessarily cause any change in the protein produced by the affected gene because 18 of the 20 amino acids have more than one coding triplet of base pairs (codon). Glycine, for instance, is coded for by GGA, GGU, GGG and GGC. This redundancy feature of the genetic code arises because the four bases, taken three at a time, allow 64 triplets to code the 20 amino acids and the three stop codons. It is called degeneracy.

point mutation

or

gene mutation

a genetic change affecting a single LOCUS, producing an alternative ALLELE of the gene, but not a gross structural change to the chromosome. The genetic change consists of an altered sequence of DNA bases, which can be of three main types:
  1. (a) a SUBSTITUTION MUTATION,
  2. (b) a DELETION MUTATION and
  3. (c) an INSERTION MUTATION, the latter two often causing a major change to the amino acid sequence of the protein structure. Compare CHROMOSOMAL MUTATION.