Questions: The nucleotide sequences of wild-type genes are 5'-GCA ATG GGC ATC GAC TGA-3'. In a mutant form, there is a single nucleotide, with an adenine addition right after methionine. The nucleotide sequences are shown in triple code. What type of mutation would this be called? (Use a codon chart.) Nonsense Missense Frameshift Silent Revertant

The answer is the third one: Frameshift.

ExplanationThe answer is the third one (Frameshift).

Explanation for each option:

1. Nonsense: A nonsense mutation introduces a premature stop codon into the sequence, leading to a truncated and usually nonfunctional protein. This is not the case here, as the mutation described involves the addition of a nucleotide rather than the creation of a stop codon.

2. Missense: A missense mutation results in a single nucleotide change that causes a different amino acid to be incorporated into the protein. This mutation involves the addition of a nucleotide, not a substitution, so it does not fit the definition of a missense mutation.

3. Frameshift: A frameshift mutation occurs when nucleotides are inserted or deleted from the DNA sequence, causing a shift in the reading frame of the codons. Since the mutation described involves the addition of an adenine nucleotide, it will shift the reading frame of the subsequent codons, leading to a frameshift mutation.

4. Silent: A silent mutation is a change in the nucleotide sequence that does not alter the amino acid sequence of the protein. The addition of a nucleotide will alter the reading frame and thus the amino acid sequence, so this is not a silent mutation.

5. Revertant: A revertant mutation restores the original function of a gene that had been previously mutated. This does not apply here, as the mutation described is an addition of a nucleotide, not a restoration of a previous mutation.

Summary: The mutation described involves the addition of an adenine nucleotide, which shifts the reading frame of the codons. Therefore, this type of mutation is called a frameshift mutation.