07Mutagens_Rep - Mutation: Mutagenesis and Repair...

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Mutation: Mutagenesis and Repair Mutagenesis spontaneous mutations replication slippage tautomeric shifts apyrimidinic site: (AP site) mutagens: radiation ultraviolet radiation pyrimidine dimers mutagens: chemicals deaminating agents: e.g., nitrous acid alkyating agents: e.g., nitroso compounds intercalators: e.g., ethidium bromide Repair of mutations direct repair T C transition by alkyltransferases by photoreactivation enzyme (PRE) A A excision repair of dimers by uvrABC endonuclease of AP sites by AP endonuclease of deaminated bases by glycosylases of mismatches by MutS and MutH post-replication repair mismatch repair recombination “repair” by RecA o error-prone systems – SOS lesion bypass – LexA – UmuC, UmuD – DNA polymerases zeta ( ζ ) and eta ( η ) Ames test for mutagenicity Photolygase – gets energy from light, damage caused by light G lesion: AP site No direct repair Lesion: methylguanine thymine dimer Subst/deltion mutation: transition BaP G No alkyltransferase for this group No direct repair here Nitrous acid transition 11 sugar N O H N N N N H  N   N   O H 3 C H 3 C H 3 C sugar H 2 N O H N N sugar H 2 N O sugar H 2 N O H H 3 C sugar H 2 N O H CH 3 N N N N N N N N N N N N N N N N N N H 2 N N N N N H 2 N O O N N H O O N N H N N N N H 2 N N N N N H 2 N O O N N H O O N N H sugar N O N sugar H 2 N O H N N N N O sugar N O N H CH 3 NH sugar N O N H sugar H 2 N OH N N N N sugar NH N N N N H OH sugar N O N CH 3 sugar N N N N N H H N H H sugar N O N N H H O sugar N O N H CH 3
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Lesion: deoxyuridine I. It’s better to clone DNA in a bacteria than use it from other people because: 1. People only make as much as they need so there’s not much extra and you would have to get it from many people. 2. Bacteria will produce a lot because many plasmids and you use promoters that cannot be regulated (shut off). Gene therapy Genetic engineering Done on humans Done on non-humans Used to treat a condition Used to manipulate for the benefit of humans Done on adults and older children (since they  know risks like cancer, to progeny, not  working, etc.) Done on embryos For somatic cells For germ cells Not heritable Heritable II. DNA fingerprinting -Done by PCR -focus on areas of the genome that vary greatly throughout the species, these areas are called polymorphic. -The most used method now is VNTR- variable number of tandem repeats (how many repeats at a certain location, the location is called a VNTR. Example for one VNTR: ------------------------------^^^^---------------------------------------------------------------------------------- primer primer ---------------------------------------------------------------------^^^^-------------------------------------------- Dr. Finklea has 30 repeats, Audre has 35 repeats and Megan has 42 But just one isn’t specific enough so about 12 different VNTRs are used. So once you have the 12 fragments you use electrophoresis.
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07Mutagens_Rep - Mutation: Mutagenesis and Repair...

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