Final answer:
A mutation that changes the amino acid sequence without altering the protein's function is known as a neutral mutation, using a chemically similar amino acid.
Step-by-step explanation:
The term for a mutation that changes the amino acid sequence of a protein without altering its function is called a neutral mutation. This type of mutation results in the use of a different, but chemically similar, amino acid. For example, a codon change that leads from AAA to AGA still encodes for a basic amino acid (from lysine to arginine), which might not affect the protein's function. This is in contrast to nonsense and frameshift mutations, which typically lead to nonfunctional proteins, or silent mutations, which do not change the amino acid sequence at all.