A frameshift mutation is a type of genetic mutation caused by insertions or deletions of a number of nucleotides in a DNA sequence that is not divisible by three. This alters the reading frame of the gene, leading to a completely different translation from the original.
Among the options provided:
- a. Deletion of a codon: This is not a frameshift mutation because a codon consists of three nucleotides, and its deletion does not alter the reading frame.
- b. Missense mutation: This is a point mutation where a single nucleotide change results in a different amino acid being incorporated into the protein. It does not cause a frameshift.
- c. Silent mutation: This is another type of point mutation where a single nucleotide change does not alter the amino acid sequence of the protein. It also does not cause a frameshift.
- d. Deletion of one nucleotide: This is an example of a frameshift mutation. Deleting a single nucleotide shifts the reading frame of the gene, leading to a completely different and often nonfunctional protein.
Therefore, the correct answer is d. Deletion of one nucleotide.