BIOL 0510 Lecture Notes - Lecture 7: Ethidium Bromide, Missense Mutation, Frameshift Mutation
7 Nov 2016
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Mutation: change in the nucleotide sequence in the genome of an organism. Missense mutation: get a different aa --> faulty protein. Nonsense mutation: get stop codon --> incomplete protein **very bad. Silent mutation: gives different codon but the aa is the same given the wobble --> no consequence on protein. Frameshift mutation: result in change in the reading frame. Downstream codons are shifted by one position so they are now all incorrect. Sometimes mistakes happen by faulty proofreading but can also have mutagens. Base analogs: substitute for bases in dna, pair with the wrong base and induce a mutation. Intercalative dyes: ethidium bromide, causes abnormal dna conformation and results in insertions and deletions. Ionizing radiation: x-rays, cosmic rays, gamma rays (high-powered) - generate hydroxyl radicals that can mutate the dna. 1920s: x-rays found to cause mutations in drosophila. Nonionizing radiation: uv light, bases of dna absorb the uv light and generate altered dna structures.
