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55 exam 4 Review

55 exam 4 Review - Prelim 4 7:30 – 9:00 PM Feb 25 2010 In...

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Unformatted text preview: Prelim 4, 7:30 – 9:00 PM, Feb. 25. 2010 In the exam: no phones no calculators no mothers Suggestions: • get a good night sleep • read the entire question, even if you think you know the answer • draw it on paper • if stumped, look for the underlying principle • if stumped, start somewhere, anywhere • pace yourself • there are no “trick” questions Multiplication rule: the probability of two independent events occurring is equal to the product of the two probabilities. rr offspring: ½ X ½ = ¼ Addition rule: the probabilility of any one or two or more independent events = sum of individual probabilities. Chance of getting one of the Rr offspring = ¼ Chance for getting the other Rr offspring = ¼ So the probability of an Rr offspring = ¼+¼=½ Codominance: both alleles have a phenotype In lentils (seeds): CD is dotted allele CS is spotted allele codominance --> CD CD X CS CS CD CS o ffspring Incomplete dominance This is not an intermediate phenotype, as in incomplete dominance If a wild-type female *(b+vg/bvg+) and a black vestigial-winged male fruit fly (bvg/bvg) are involved in a test cross, which of the following genotypes of offspring are recombinant, and what is the expected number of recombinant individuals among 500 progeny if the map unit distance between these genes is 10 map units? b+vg bvg b+vg/bvg b + vg + 25 bvg 25 bvg + bvg/bvg+ b+vg+/bvg bvg/bvg # recombinants X 100 = 10 map units total offspring (ie 500) so, # recombinants = 50 *written this way (instead of b+b/vg+vg) so you know which alleles are linked. Telomeres: how do they protect? somatic cell divisions Overview of DNA synthesis Cell divisions bad news germ line (or cancer cells) telomerase adds nucleotides Transcription Remember this: Nucleotides are added at the 3’ end of the growing strand Where, when and why does this happen? 60 nucleotides/sec Life cycle of an enveloped RNA virus ! " ! # ! The tryptophan (trp) operon in E. coli the trp operon is normally on, but can be turned off. This is common in anabolic pathways. G o o d L u c k ...
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