BIO SCI M125 Chapter 7-8: cs4
21 Dec 2016
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Document Summary
Translocations (gene to another sequence) - philadelphias - bad due to gene fusion. 2 steps to mutation: damage, complementary synthesis of the unrepaired nucleotide. Dna damage by water, radiation, uv, hydrolytic damage, Oh- nucleophilic attack in high ph=> high hydrolysis. Deamination is hydrolytic attack and affects bases w/ amino group namely cytosine, adenine, guanine, and 5-methylcytosine. Deamination of cytosine is really bad/mutagenic because uracil readily pairs with adenine instead of guanine. 5-methylcytosine to thymine bad because repair mechanisms cannot recongize thymine as mutation until next round of replication. G - c permanently deaminated to u - a. Still ok because dna repair mechanisms recognize u as foreign nucleotide. Abasic site in single stranded dna - occurs more in purines. Damage can lead to point mutations and strand breaks. Use different potental carcinogens that may reverse mutate the gene to synthesize hystidine.
