And let's begin by discussing insertion deletions. So, to insert something or to delete something means we're basically either placing nucleotides into the DNA or we're removing nucleotides from that DNA sequence. Now, an insertion or deletion of a number of nucleotides that is not a multiple of three, that is not a multiple of the codons that exist in the genetic code will cause the reading frame to shift, which will change the amino acid sequence of the polypeptide chain. And this is known as a frame shift mutation. So insertion deletions can form frame shift mutations in which the entire reading frame, the entire mRNA sequence, is shifted. And that means that completely new codons will be read by our ribosomes, and a completely new sequence of amino acids will be produced.