🌠 Alteration of the sequence of bases in DNA can alter the structure of proteins


The Cause of Mutations

The Effect of Mutations


 

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. Mutation occurs spontaneously.

 

There are different types of mutation:

 

Deletion where one or more nucleotide bases are deleted. AGTCA becomes AGCA

 Substitution where one or more nucleotide bases are replaced by others. AGTCA becomes AGTCG

 

 

 Addition where one or more nucleotide bases are added as extra. AGTCA becomes ATGTCA

Inversion where a section of DNA is inverted e.g. AGTTCATTCCAGG becomes AGTTCCCTTAAGG

Duplication where one or more nucleotide bases are repeated e.g. AAGTCG becomes AAGTCGAAGTCG

Translocation where one or more nucleotide bases are moved between non-homologous chromosomes e.g. AAGCTT on human chromosome 1 is moved and becomes AAGCTT on human chromosome 3

 

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 substitutions