Final answer:
A mutation where cytosine is replaced by adenine is considered a point mutation and can cause different types of mutations—such as silent, missense, or nonsense—that affect the protein produced. The mutation can also provoke a frameshift if it's part of an insertion or deletion, disrupting the entire downstream amino acid sequence and protein function.
Step-by-step explanation:
When a mutation occurs and cytosine is replaced with adenine in DNA, this is called a point mutation. The affected codon in the mRNA transcript will now have uracil instead of guanine during transcription because adenine pairs with uracil in RNA. As a result, this may lead to different outcomes:
- A silent mutation, if the new codon still codes for the same amino acid, resulting in no change to the protein sequence.
- A missense mutation, if the new codon codes for a different amino acid, potentially altering the protein's function.
- A nonsense mutation, if the new codon becomes a stop codon, leading to a truncated and likely nonfunctional protein.
In addition to changing the codon sequence, this type of mutation can also cause a frameshift, if it occurs as part of an insertion or deletion, by shifting the reading frame of the mRNA. A frameshift mutation can change the entire amino acid sequence downstream of the mutation, which often results in a completely dysfunctional protein.