AGB 121: Principles of Animal Genetics and Population Genetics (2+1)

NONSENSE MUTATION

• Any mutation that changes a codon into a codon that codes for a STOP signal (termination codon) is called a Nonsense mutation.
• The three termination codons are UAA, UAG, and UGA.
• For example : if the codon UAC ( for tyrosine ) undergoes a one base substitution (C --> G) it becomes UAG, a termination condon.
  As a result is a premature termination of translation and the protein / polypeptide is shorter than usual and does not contain all the amino acids.
• Such protein / polypeptide are likely to be biologically inactive or nonfunctional.