BIS101-001_Midterm2BKey

BIS101-001_Midterm2BKey - BIS101-01(Chan Winter 2009...

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BIS101-01 (Chan) Winter 2009. Midterm 2B Key note: you would need to show more working for some bacterial genetics questions in order to receive full points 1) You performed a conjugation experiments with an Escherichia coli HfrC strain with the genotype Hfr pro + arg + ser + met + str s and an F - recipient of the genotype F - pro - arg - ser - met - str r . The mating was interrupted at several times and plated on several different media with the following results. The table below shows the number of colonies. Time (min.) Minimal medium plus streptomycin plus arginine proline proline proline serine arginine serine arginine methionine serine methionine methionine 0 0 0 0 0 10 0 44 0 0 20 20 179 0 19 30 186 601 5 190 40 746 788 299 750 A. (6 pts) What is the order of the four auxotrophic genes with respect to the starting point of transfer (0)? 0 - met - pro/ser - arg The order of pro and ser cannot be unambiguously determined from the above data. B. (4 pts) How could you resolve any uncertainties in your answer to part A and explain why? Recombination data would remove the uncertainty in the conjugation data about the order of the pro and ser marker. Recombination data could measure the distance between pro and arg as well as between ser and arg . A smaller distance in the former and a larger distance in the latter would, for example, suggest an order of ser - pro - arg . 2) (10 pts) A few questions about the structure of DNA. A. (2 pts) Define a NUCLEOTIDE. A nucleotide is the building block of DNA consisting deoxyribose (sugar), a nitrogenous (term nitrogenous not necessary) base (adenine, thymidine, guanine, cytosine) and phosphate. B. (2pts) DNA contains 4 bases. If you measure the amount of each base as a percentage of the total, which bases are guaranteed to have the same % no matter which genome you choose? %A = %T, and %G = %C 1
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C. (4 pts) Name two inherent chemical parameters that determine the stability of duplex DNA. Hydrogen bonds through Watson-Crick base pairing Stacking interactions (hydrophobic) between the planar bases Base composition of double stranded DNA will change its melting temperature D. Name two ways in which you can experimentally manipulate the stability of duplex DNA. (4pts)
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This note was uploaded on 01/29/2010 for the course BIS 101 taught by Professor Simonchan during the Winter '08 term at UC Davis.

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BIS101-001_Midterm2BKey - BIS101-01(Chan Winter 2009...

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