Final answer:
The correct term for a point mutation that specifies the same amino acid is a silent mutation. This type of mutation does not alter the amino acid sequence of the protein, and it occurs because of the redundancy in the genetic code.
Step-by-step explanation:
A point mutation in a protein-coding gene that results in the specification of the same amino acid is termed a silent mutation. This occurs because the genetic code has a redundancy, which allows multiple codons to code for the same amino acid. Hence, even with a base pair change, the resulting amino acid sequence of the protein remains unchanged. An example of a silent mutation would be a change from the codon CCA to CCU, both of which code for the amino acid proline.
On the other hand, a missense mutation results in the codon coding for a different amino acid, which may have varying effects on the protein function depending on the nature of the substituted amino acid. The sickle cell disease is an example of a disease caused by a missense mutation. A nonsense mutation is a point mutation that results in a codon becoming a stop codon, leading to premature termination of protein synthesis. A deletion leading to the loss of a single nucleotide can result in a frameshift mutation, which alters the entire downstream amino acid sequence.