CAS BI 213 Study Guide - Final Guide: V(D)J Recombination, Regulatory Sequence, Hereditary Nonpolyposis Colorectal Cancer
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This blue: both lecture and book mentioned notes. Be adjacent & same strand. (figure 6. 19; figure 6. 18a) Cyclobutane ring caused by saturation of double bonds between c5 and c6 distort shape of dna strand (creates a bump) Causes guanine to base pair with thymine instead of cytosine. Alkylating agents: transfer methyl/ethyl groups to dna base (chemical: direct reversal of dimers caused by uv light modifiers, photoreactivation: energy from visible light is used to break cyclobutane ring. Pyrimidine bases remain in dna and are restored to normal state. Common in prokaryotes and eukaryotes, but not present in placental mammals (i. e. humans: repair by enzyme o6-methylguanine methyltransferase (figure 6. 20) Transfers the methyl group from methylguanine to a cysteine residue in its active site. Common in prokaryotes and eukaryotes, including humans. 6. 21: most important in dna repair in prokaryotes and eukaryotes, damaged dna is recognized, removed, and filled by dna polymerase, base-excision repair.