Question

By definition, if the DNA of a cell undergoes a spontaneous mutation, is was NOT due to

A.) Errors in DNA replication

B.) Insertion of transposons

C.) Exposure to radiation

D.) Spontaneous depurination of nucleotides

Answer 1

Option C

Mutations are changes in DNA which may or may not affect the phenotype of the organism.

If mutations occur in somatic cell of an individual, then they affect the individual only and are not passed on to the next generation. Such mutations are called as somatic mutations.

If mutations occur in germline cell of an individual, then there passed on to the next generation. Such mutations are called as germinal or germline mutations.

There are spontaneous and induced mutations.

Spontaneous mutations are those which arise due to errors in DNA replication, transposable elements and spontaneous lesions.

Errors arise during DNA replication and are corrected by mismatch repair system of the cell. Any problem in the mismatch repair system leads to the generation of spontaneous mutations.

Transposons are jumping genes. They are the segment of DNA which can jump from one location to the other. If they jump into a coding region of DNA then they affect the structure and therefore function of the protein encoded by that region.

Induced mutation are those which are caused by environmental factors. These environmental factors are called as mutagens.

A mutagen is a substance which has a potential to cause mutation. Mutagen can be a physical factor like X-rays for Gamma Rays or UV rays or a biological factor like viruses or Helicobacter pylori or some chemical light aflatoxins and benzoyl peroxide.

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