What is a nonsense mutation?

A nonsense mutation is characterized by the alteration of a codon in the DNA sequence that results in the premature termination of protein synthesis. Specifically, this type of mutation changes a sense codon, which typically encodes an amino acid, into a stop codon. Stop codons signal the ribosome to halt translation, leading to the production of a truncated protein. This can have significant effects on the function of the resulting protein, often rendering it nonfunctional or having a detrimental effect on the organism.

In contrast, the other options describe different types of mutations. A mutation that changes an amino acid to a different one refers to a missense mutation, which alters the codon sequence in a way that produces a different amino acid but does not necessarily lead to an early stop. A deletion of one or more bases in DNA alters the sequence and can lead to frameshift mutations, which cause significant shifts in the reading frame but do not specifically describe what defines a nonsense mutation. Lastly, a silent mutation does not change the amino acid produced, therefore not affecting protein function, and does not lead to premature termination.