BIOS 20175 Lecture Notes - Lecture 11: Apoptosis, Exonuclease, Helicase
25 Jul 2020
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Good mutation note: most mutations are neutral and have no effect, but evolution is dependent on mutations and selection and this has to mean that some mutations have to be good. Basic mechanism are in cells to prevent further disaster. Cell cycle checkpoints that arrest cycle progression when standards are not met. Apoptosis that occurs when the dna damage is way to extensive. Homology dependent repair-- mutations on one strand of the dna can be fixed using the undamaged complementary strand as a template. Exonuclease repair: removing defective nucleotides and replacing them with the correct base. Targets mismatched base pairs that were not caught by dna pol and fixes them based on identification of the parent strand. Some bacteria use the process of methylation to help identify the parent strand, which adds methyl bases to the parental template. Bacteria can see the methyl tags and know which base is correct.
