BIOL 205 Lecture Notes - Lecture 1: Frameshift Mutation, Intellectual Disability, Base Pair
19 Jan 2015
School
Department
Course
Professor
Document Summary
Mutations due to trinucleotide repeats located in non-coding regions: cgg repeat expansion. Leads to mental retardation and is associated with autism: shortening of chromosome arms, breakdown in repair system. Induced mutations: mechanisms of mutagenesis, incorporation of base analogs, specific mispairing, intercalating agents, base damage. Incorporation of base analogs: chemicals resembling normal nitrogen bases get incorporated into dna, alternate pairings, specific mispairing, causes mispairing. Intercalating agents: slips between bases, causes frame shift mutation, base damage, results in base pair substitutions and/or replication blocks. Ionizing radiation: short wavelength, high energy, eg. X-rays and gamma rays: penetrates deeply into biological molecules, base deletions, cross-linking, chromosome breaks, single nicks in dna strands, creates free radicals. Less energy: cannot penetrate deeply into biological molecules, causes of formation of crosslinked thymine dimers and 6-4 photoproducts, may cause mutations when dna strand is replicated. Methods for testing agents as mutations: ames test (how mutagenic a compound might be) Xerdoerma pigmentosum and cockayne syndrome breakdown in nucleo-excision repair.
