Nonsenssimutaatio

Nonsenssimutaatio, also known as a nonsense mutation, is a type of point mutation that results in a premature stop codon. This means that the sequence of DNA is altered in such a way that a signal for the termination of protein synthesis is encountered earlier than it should be. During translation, the ribosome reads the messenger RNA (mRNA) sequence and uses it to build a protein. Genes contain codons, which are three-nucleotide sequences that specify particular amino acids. Some codons act as stop signals, telling the ribosome to end protein synthesis. A nonsenssimutaatio changes a codon that normally codes for an amino acid into one of these stop codons.

The consequence of a nonsenssimutaatio is the production of a truncated protein. This shortened protein is often non-functional or has significantly reduced function because it lacks essential parts of its normal structure. The severity of the effect depends on where the premature stop codon occurs in the gene. If it happens early in the sequence, the resulting protein will be very short and likely completely inactive. If it occurs later, some functional parts of the protein might still be produced, leading to a partially functional, though often still problematic, protein. Nonsenssimutaatiot are implicated in a variety of genetic disorders, as they can disrupt the function of critical proteins. For example, cystic fibrosis and some forms of muscular dystrophy can be caused by nonsense mutations.