BIOL 205 Lecture Notes - Lecture 7: Xeroderma Pigmentosum, Pyrimidine Dimer, Bruce Ames
Document Summary
Trinucleotide repeats in the fmr-1 gene (fragile x mental retardation gene) hinder transcription. Mechanisms of mutagenesis: incorporation of base analogs, specific mispairing, intercalating agents, base damage, incorporation of base analogs. Chemicals that resemble normal nitrogen bases- get incorporated into dna. Alternative pairings for 5-bromouracil (5-bu)- an analog of thymine. Intercalating agents- slips between bases causes insertion or deletion of a single nucleotide pair. A deadly toxin produced by the fungus aspergillus. Results in base pair substitutions and/or replication blocks: physical mutagens come into two main types. Can cause: base deletions, single nicks in dna strands, cross-linking, chromosomal breaks. Causes the formation of cross- linked thymine dimers and 6-4 photoproducts. They may cause mutations when that dna strand is replicated. Testing methods can determine if an agent is a mutagen: many different kinds of tests have been used to evaluate mutagenicity.
