Final answer:
The change from a pyrimidine (cytosine) to a purine (adenine) in DNA is known as a transversion substitution, which can impact DNA structure and potentially alter the protein encoded by the gene.
Step-by-step explanation:
The change from a pyrimidine such as cytosine to a purine such as adenine in DNA damage is known as a transversion substitution. This type of mutation involves the replacement of a pyrimidine base with a purine base, or vice versa. Transversion mutations can have various causes, such as chemical exposure to mutagens like base analogs or alkylating agents, or physical damage from ionizing radiation, which can lead to breakage of the DNA backbone or alter base-pairing rules.
Additionally, nonionizing radiation, like ultraviolet light, may introduce pyrimidine dimers that can result in mutations during DNA replication and transcription if not correctly repaired. When cytosine is replaced with adenine, this changes the structure of the DNA, potentially altering the protein encoded by the gene if the mutation occurs within a coding region.