Final answer:
A nonsense mutation changes a codon to a premature stop codon, leading to the creation of truncated, often non-functional proteins, with serious potential consequences such as genetic disorders or cancer.
Step-by-step explanation:
When a nonsense mutation occurs in the DNA sequence, it alters a codon that normally specifies an amino acid to a stop codon. Translation of the mRNA is then terminated prematurely, leading to the production of a shorter, and often non-functional, protein. This can have various consequences depending on where in the gene the mutation occurs; the earlier the mutation, the more truncated the protein will be. Nonsense mutations can be particularly deleterious because they can halt the formation of essential proteins, potentially leading to genetic disorders or cancer. Unlike missense mutations, which may retain some function of the protein, nonsense mutations frequently result in a complete loss of function due to the truncated protein lacking critical domains necessary for its activity.