Types of Mutations

Types of Mutations

	Types of Mutations - I Chromosome Mutations - gross changes in chromosomes. A. Changes in the number of chromosomes. 1. Euploidy - variation in the number of sets of chromosomes. a. Haploidy (Monoploidy) - one set of chromosomes (n) : ABC b. Polyploidy-three or more sets of chromosomes. Triploidy-3 sets of chromosomes (3n) : ABC, ABC, ABC. Tetraploidy--4 sets of chromosomes (4n): ABC, ABC, ABC, ABC. Pentaploidy-5 sets of chromosomes (5n) : ABC, ABC, ABC, ABC, ABC. Hexaploidy (6n), Septaploidy (7n), Octoploidy (8n), etc
2. Aneuploidy - variation in the number of chromosomes of a set. a. Reduction in the normal number of chromosomes. Monosomics - Ioss of one chromosome (2n-l) : ABC, AB. Double monosomics - Ioss of 2 different chromosomes (2n-l-1): ABC, A. NuIlisomics - loss of a pair of homologous chromosomes (2n-2) : AB, AB: b. Increase in the number of chromosomes (polysomies). Trisomies - presence of 1 extra chromosome (2n+ 1) : ABC, ABC, A.
Double trisomics - 2 different extra chromosomes (2n + 1 + 1) : ABC, ABC, AB. Tetrasomics - an extra pair of homologous chromosomes (2n+2): ABC, ABC, AA. pentasomics (2n+3), Hexasomics (2n+4), Sepiasomics (2n+5), etc. B. Changes in the structure of chomosomes. a. Loss or addition of segments of chromosomes. Deletion (deficiency) - Ioss of a segment of a chromosome Duplication - repetition of a segment of a chromosome.
b. Changes in the normal arrangement of, genes in the chromosome. Translocation - exchange of segments between two non-homologous chromosomes, resulting in new chromosomes. Inversion - change in the linear order of genes by rotation of a section of a chromosome through 180 degrees. II. Gene Mutations or Point Mutations - changes in the nucleotide sequence of a gene. Deletion - removal of one or more nucleotides from a gene. Insertion - addition of one or more nucleotides in a gene. Substitution (replacement) - replacement of a nucleotide by another. Inversion - reversal of a series of nucleotides in the gene. Deletion and insertion - removal of a nucleotide at one point in the gene and addition of a nucleotide at another point.

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Suppressor Genes Frameshift Suppressions Molecular Basis of Mutations Spontaneous Mutations Tautomerism Induced Mutations Chemical Mutagens Base Analogues Agents Modifying Purines and Pyrimidines OR Agents Labilize the Bases Agents Producing Distortions in DNA Radiations Types of Mutations

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