base-pair substitution

A point mutation is a genetic alteration where a single base pair in the DNA sequence is changed. These mutations often occur due to errors during DNA replication or can be caused by environmental factors like X-rays or ultraviolet radiation.12

There are two main types: transitions, where a purine base is replaced by another purine, or a pyrimidine by another pyrimidine; and transversions, where a purine is replaced by a pyrimidine, or vice versa. These changes can lead to different outcomes at the protein level, including silent mutations (no change in amino acid), missense mutations (different amino acid, potentially altering protein function), and nonsense mutations (premature termination of protein synthesis). Point mutations are fundamental to understanding genetic variation and the development of diseases.13