🐞 Gene Mutation


The Cause of Mutations

The Effect of Mutations

Mutations and Cancer


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The Cause of Mutations

Mutations are a random occurrence during DNA replication and the rate of mutation is influenced by external factors such as UV radiation. There are different types of mutation:

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Deletion where a nucleotide base is deleted. AGTCA becomes AGCA.

Substitution where a nucleotide base is replaced by another. AGTCA becomes AGTCG.

Insertion where a nucleotide base is added as extra. AGTCA becomes ATGTCA.

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The Effect of Mutations

Since the genetic code is degenerate, it’s possible that a mutation won’t have any effect whatsoever! This represents silent mutations. If 2 different triplet codes translate into the same amino acid, the polypeptide chain will remain unchanged. This of course only applies to applies to substitutions.

Another scenario where a mutation may cause no effect is if it arises in an intron. Since these are removed before mRNA is translated, no mutations would be carried along.

What happens if a base is deleted or added?

The genetic code is non-overlapping, so the error cannot simply be overlooked and the following triplets read correctly. The entire subsequent code will be shifted. This is called a…