iGen3 07-04

Non-sense mutations in DNA

The DNA template strand sequence 5'-CTTAGG-3' DNA [top left) mutates to a 5'-CTAGGA-3' [top right]. The 5'-AAG'-3' mRNA codon therefore changes to a 5'-UAG-3' codon, which instead of adding a Lys (K) amino acid, introduces a release factor that terminate the protein prematurely. This is called a non-sense mutation, because the resulting codon has 'no sense', rather than having an incorrect or miss-sense for another amino acid.

[HOMEWORK: what is the corresponding mutation in the DNA sense strand?].

Figure © 2010 PJ Russell, iGenetics 3rd ed.; all text material © 2014 by Steven M. Carr