Mutations in DNA can be classified into three main types based on their effects on the protein sequence: silent mutations, missense mutations, and nonsense mutations.

Silent Mutations
Silent mutations are alterations in the DNA sequence that do not result in a change in the amino acid sequence of the protein. This phenomenon occurs because the genetic code is degenerate; multiple codons can specify the same amino acid. For instance, the codons $GGU$, $GGC$, $GGA$, and $GGG$ all encode the amino acid glycine. Consequently, a change in the third nucleotide of such codons may not alter the corresponding amino acid.

Missense Mutations
In contrast, missense mutations are changes in the DNA sequence that lead to a substitution of one amino acid for another in the protein. This type of mutation arises from a single nucleotide change that creates a different codon, which encodes a distinct amino acid. The impact of a missense mutation on protein function can vary widely depending on the specific location and nature of the amino acid change.

Nonsense Mutations
Nonsense mutations introduce a premature stop codon into the DNA sequence, resulting in a truncated protein. This premature termination can significantly affect the protein’s function, as the shortened protein may be incapable of carrying out its normal role or may be targeted for degradation by the cell.

In summary, the type of mutation and its position within the gene can greatly influence the characteristics and functionality of the resulting protein. A thorough understanding of these different mutation types is crucial for studying genetic disorders and developing effective treatments.