A missense mutation occurs when there is a mistake in the DNA code and one of the DNA base pairs is changed, for example, A is swapped for C. This single change means that the DNA now encodes for a different amino acid, known as a substitution.

What is missense mutation?

Listen to pronunciation. (MIS-sens myoo-TAY-shun) A genetic alteration in which a single base pair substitution alters the genetic code in a way that produces an amino acid that is different from the usual amino acid at that position.

What stage does mutation occur?

Mutations occur during DNA replication prior to meiosis. Crossing over during metaphase I mixes alleles from different homologues into new combinations.