Insertion Mutation - a type of frameshift mutation. Occurs when a nucleotide is added to a DNA molecule. It causes all of the other nucleotides, from the point of insertion to the end of the DNA strand, to move down one position. The impact on the protein strand from this type of mutation is often quite profound, leading to different amino acids from the mutation point to the end of the protein. At times, an insertion mutation can lead to an early stop codon, meaning that the protein will be missing amino acids. At other times, an insertion mutation can lead to a missing stop codon, meaning that the protein has more amino acids than it should. Either way, the proteins that are formed from this type of mutation will generally have a different function than the original protein, or no function at all.