And this in turn changes the codons that are read by the ribosome. And this changes the sequence of amino acids that are produced on the polypeptide chain. And this result usually leads or produces a nonfunctional protein. So we see that any deletion or insertion of a nucleotide that is not a multiple of three nucleotides will cause such a mutation, such a shift in the frame. And such a mutation is commonly known as a frame shift mutation. So we see that a frame shift mutation is caused when we have either an insertion or a deletion of a nucleotide or nucleotides that are not a multiple of three.