Mutations: Types, Mechanisms, Mutagens and Ames test

Mutations: Types, Mechanisms, Mutagens and Ames test

January 3, 2022

Mutations: Types, Mechanisms, Mutagens and Ames test

Mutation

  • Any inheritable physical change in the DNA sequence of an organism is a mutation.
  • Mutations are the source of the altered versions of genes that provide the raw material for evolution.
  • Most point mutations have no effect on the organism, especially among the eukaryotes, because a large portion of the DNA is not in genes and thus does not affect the organism’s phenotype.
  • Of the mutations that do affect the phenotype, the most common effect of mutations is lethality, because most genes are necessary for life.
  • Only a small percentage of mutations causes a visible but non-lethal change in the phenotype.

Types of mutations (types of cells)

Somatic mutation

  • Occur in all the cells of the body, excluding the germline
  • Affects subsequent somatic cell descendants
  • Not transmitted to offspring
  • Mostly resulted in tumor or cancer

Germ line  Mutation

  • Mutations that occur in the germline cells
  • Possibility of transmission to offspring
  • Inheritable genetic disorders

Types of Mutation (Sources)

Sponaneous Mutation

Mutation that occur without the known cause. It may occur due to:

  • Inaccuracy in replication by DNA replication machinery
  • Inefficiency of the DNA repair mechanisms for the repair of damaged DNA
  • Degree of exposure to unknown mutagenic agents in the environment

Induced Mutation

Mutations are induced by exposure to physical (radiation; UV or ionizing radiation) or chemical mutagens.

  • Hermann J. Muller and Edgar Alternburg measured the frequency of X-linked recessive lethal mutations in Drosophila.
  • Muller demonstrated that exposing Drosophila sperm to X-rays increased the mutation frequency

To test the knowledge on mutations click on MCQs on mutations and mutagens

 

One response to “Mutations: Types, Mechanisms, Mutagens and Ames test”

  1. […] This post provides 35 MCQs on mutations and mutagens. For detail, please click on Mutations: Types, Mechanisms, Mutagens and Ames test […]

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