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Unformatted text preview: Biological Sciences 101 Dr. Mark Sanders Summer Session II 2008 Midterm II Exam Key 1a. phenylalanine and alanine (1 pt/each) 1b. phe-leu-ala or ala-leu-phe (6 pts) 1c. Double crossover, with one site outside phe and the other between leu and ala (4 pts) 1d. This class of transducants requires a quadruple crossover that does not occur in this experiment. (2 pts) 2. (1 pt/item, accurate placement is crucial) 5 ______________________________________________ 3 DNA 3 _____h______a __________c_________________d_______ 5 mRNA i5 __b ____e______________j____g__3f 3a. cip-mdt = 548 + 4/1200 = 0.46; cip-rpb = 548 + 555/1200 = 0.92 (2 pts work, 1 pt answer/each) 3b. cip-rpb-mdt or mdt-rpb-cip (3 pts) 3c. This is the quadruple crossover class (2 pts) 4a. met+ ala+/- trp +/- (-1 pt for each incorrect genotype) 4b. Yes, all colonies must have been transduced with met+ to grow on the selection plate. (2 pts) 4c. Plate A: met+ ala+ trp+/- Plate B: met+ ala+/- trp+ Plate C met+ ala+ trp+ (2 pts/plate) 4d. Plate A: met+ ala+ trp- Plate B: met+ ala- trp+ (2 pts/plate) 4e. Colonies growing on plate A could have either of the two genotypes given above (in the answer to part c), but since none of these colonies grow on the minimal medium plate, none are trp+, thus all colonies on plate A are met+ ala+ trp-. 5a. This reaction contains the four normal nucleotides, dATP, dTTP, dCTP, dGTP, and the dideoxynucleotide of adenine, ddATP. (3 pts) 5b. Answer to include: a) PCR initiates from a primer, b) PCR uses the sample fragment to replicate a new DNA strand, c) replication continues until a ddNTP is incorporated (1 pt/item) 5c. Answer to include: a) ddNTPs are missing an oxygen molecule at the 3 carbon. The 3 carbon of ddNTP ia bound by an H, rather than an OH as in dNTPs, b) without the hydroxyl, the 3 end of the ddNTP cannot form a phosphodiester bond with another nucleotide, c) synthesis of the nascent DNA strand terminates with the ddNTP. (1 pt/item) 6. (2 pts/line of the table, 1 pts for polarity of each line) [Write in polarity before printing] T C C A T G C T A C C A Coding strand A G G T A C G A T G G T Template strand U C C A U G C U A C C U mRNA transcribed A G G U A C G A U G G A Appropriate tRNA anticodon Ser r Met t Leu u Pro o Amino Acids in polypeptide [Note: coding is 3 5, template is 3 5, mRNA is 5 3 and tRNA is 3 5] 7a.The gene order and alleles are t-H-L/T-h-l or L-H-t/l-h-T (6 pts) 7b. The recombination fractions are 7b....
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This note was uploaded on 09/30/2008 for the course BIS 101 taught by Professor Simonchan during the Summer '08 term at UC Davis.
- Summer '08