Types of Mutations

Point Mutation Change in one base of the gene sequence. Original: The fat cat ate the wee rat. Mutation: The fat hat ate the wee rat.

Point Mutation Example Sickle Cell Disease an inherited blood disorder that affects red blood red blood cells can become sickle-shaped (crescent shaped) When sickle-shaped cells block small blood vessels, less blood can reach that part of the body. Tissue that does not receive a normal blood flow eventually becomes damaged. This is what causes the complications of sickle cell disease.

Frame-shift mutation one or more bases are inserted or deleted, the equivalent of adding or removing letters in a sentence This type of mutation can make the DNA meaningless and often results in a shortened protein Original: The fat cat ate the wee rat. Mutation: The fat caa tet hew eer at

Frame-shift Mutation Example Tay-Sachs Disease: Fatal Genetic Lipid Storage Disorder It affects an enzyme that catalyzes reaction to break down a certain kind of fatty acid in cells Over time, this fatty acid will build up in nerve cells making them useless Infants will become blind, deaf, and unable to swallow, then paralyzed and continue to deteriorate

Deletions Mutations that result in missing DNA These can be small, such as the removal of just one "word," or longer deletions that affect a large number of genes on the chromosome. Original: The fat cat ate the wee rat. Mutation: The fat ate the wee rat.

Insertion Mutations that result in the addition of extra DNA Original: The fat cat ate the wee rat. Mutation: The fat cat xlw ate the wee rat.

Inversion an entire section of DNA is reversed Original: The fat cat ate the wee rat. Mutation: The fat tar eew eht eta tac.

Effects of Mutations No effect, if mutation codes for same amino acid, thus the same protein. Ex. ATA = UAU codes for amino acid tyrosine. If a mutation occurred and changed ATA to ATG, then ATG=UAC which also codes for tyrosine, so no change. Positive effect, if mutation changes a protein and creates a different protein which is beneficial to the organism. Negative effect, if mutation changes a protein and creates a different protein which is harmful to the organism.

Discussion Questions How do you think that these would affect the structure of a protein? What consequences could these mistakes have? Which do you think would have the greater effect: a point or a frame-shift mutation?