Final answer:
Cytosine deamination in DNA creates uracil, resulting in a mutation. This mutation is fixed by the base excision repair system, which removes the uracil and replaces it with the correct cytosine residue.
Step-by-step explanation:
When cytosine spontaneously deaminates in water, it forms uracil. Within the context of DNA, this chemically altered base is referred to as a mutation. The repair process for this type of DNA damage involves the enzymatic removal of the uracil and replacement with the correct deoxycytidine phosphate residue to maintain the integrity of the genetic information. The specific type of repair system that handles this type of mutation is called base excision repair.
Deamination events lead to the threat of GC base pairs being erroneously replaced by AT base pairs during DNA replication. The uracil resulting from cytosine deamination can misleadingly pair with adenine, promoting a GC to AT mutation in the subsequent rounds of replication. However, precise DNA repair mechanisms are capable of recognizing uracil within DNA and excising it, ensuring that genomic stability is maintained and mutational frequency is controlled.