Frameshift Mutation

Insertion or deletion of bases changing the reading frame of the code words, leading to new amino acid sequences from the site toward the carboxyl end of the polypeptide (see Fig. F44). If one or two bases are either lost or gained, the genetic message from that site is generally garbled, whereas if the loss or gain involves triplets there is a possibility to continue reading in a normal manner. Frameshift mutations are caused frequently by acridine dyes and cross-linking mutagens. The discovery of frameshift mutagens contributed to the recognition that the genetic code relies on nucleotide triplets. Frame shift mutation can be represented by the following folly:

Figure F44.

Frameshift mutation