LIFESCI 3 Lecture 10: Lecture 10
Document Summary
Does not transfer to next generation, but affects all progeny of those somatic cells. Conservative - new aa is in same aa group. Non-conservative - new aa is in a different aa group. Caused by: genotoxic chems in environment, by-products of metabolism, uv light, ionizing radiation, copying errors by dna polymerase. 5-m c is a modified base, c is methylated. This mistake is caught and corrected well b/c methylation of c is common. Mismatch between u and g --> correction made. Base is removed, backbone intact but cannot form base pair. Dna forms h bond between base pair before phosphodiester bond. No a/g base present -> deletion/frameshift mutation occurs. Use nuc excision repair to fix distorted dna shape. Flat structures allows it to insert between bases/strand (intercalate) Main dna polymerase delta uses 3" to 5" exonuclease to prevent mutations/proofread. Pauses, transfers 3" end to exonuclease site, incorrect mispaired base is removed, 3" end transferred back to polymerase site.
