Instructor: Dr. Zhongchi Liu3236 H.J. Pattersom Hall Phone: [email protected]/CBMG/faculty/liu/liu.htmlTA: Jennifer Baxter2114 (Lab) or 2114 (Office) Microbiology BuildingPhone: [email protected] the course: www.life.umd.edu/classroom/BSCI410-Liu/BSCI410/Lecture 2: Mutation and its effectRead: Ch 7 p192-193; 196-198; 200-205Figs: 7.2; 7.6; 7.7; 7.8; 7.12; 7.21;7.22; 8.15; 8.16; -Mutation type-Mutational effect-Spontaneous Mutation-MutagensFig. 7.21Mutations1. Substitution-1 base --> one of the three other basesTransition: purine --> purine or pyrimidine --> pyrimidine A--> G or G--> A T--> C or C--> TTransvertion: purine --> pyrimidine or vice versa A--> T, C; G -->T,C; T-->A, G; C-->A,G2. Deletion or insertion-often causes frameshift mutationcauses missense, nonsense, silent, neutral or splicing mutational effects 3. Chromosomal rearrangementinversion or translocation can change multiple genesEffects of point mutations tyrosine TAT, TACTAT -> CAT tyr -> his missenseTAT -> TAA tyr -> stop nonsenseTAT -> TTT tyr -> phe neutral in many casesTAT -> TAC tyr-> tyr silentFig. 7.22Fig. 8.15Fig. 8.16Fig. 7.2Spontaneous mutationsSpontaneous mutation is rare: 2-12X 10-6 (per generation per gene)Spontaneous mutations can be caused by a. mistakes made during DNA replication (error rate 10-9)b. environmrntal effect: UV light: thymidine dimer X-ray: break sugar-phosphate DNA back boneOxidative damages: G --> 8-oxodG (pair with A)c. chemical changes (hydrolysis):depurination; A,G --> Odeamination: C--> UFig. 7.8Fig. 7.7Mutagen treatment greatly increases the mutation rateExposure to X-ray, UV lightChemical treatment: base analogs 5’-bromouracil (=T or rarely C) hydroxylating agent (add OH-group to C) alkylating agent such as E!MS (ethylmethane sulfonate) deaminating agent such as nitrous acid intercalating agent such as Acridine OrangeTransposons that insert into a gene and disrupt the normal reading frame MutagensFig. 7.12a1Chemical MutagensFig. 7.12a2Fig. 7.12b1Fig. 7.12b2Fig. 7.12c1Fig.
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