Summary

DNA damage can cause changes to the DNA sequence. This can happen through errors during replication, exposure to normal byproducts of metabolism, or exogenous causes like exposure to carcinogens or radiation. The changes to the DNA sequence are called mutations. Most mutations do not impact the function of genes and therefore do not affect the phenotype of an organism. These are neutral mutations. However, other mutations do affect the function of a gene and the phenotype of the organism.

Mutations can be classified depending on the cell affected, the change to DNA sequence, the change to protein sequence, or the change to protein function.