BIO250Y Exam December 2000 ANSWERS: (1) dbdbb (6) daeee (11) ddead (16) bdbca (21) bccbd (26) ecceb (31) adbca (36) cdcdd (41) ecbad (46) baaab 1) Which of the following statements concerning structure and synthesis of DNA are correct? 1. Purines are linked via their nitrogen in position 9 to the 1' carbon of deoxyribose. 2. The pentose sugar in DNA has an hydroxyl group on the 2' carbon. 3. Ribonucleoside triphosphates are used to elongate DNA. 4. In the DNA double helix, 2 hydrogen bonds form between the complementary bases adenine and thymine. 5. A piece of double stranded DNA that is rich in G and C residues has a higher Tm in comparison to one that is rich in AT residues. a. 2,3,4,5 b. 2,4,5 c. 1,2,3,4 d. 1,4,5 e. 1,4 2) Which of the following statements concerning RNA are correct? 1. RNA is synthesized in the 3' to 5' direction. 2. RNA contains ribose. 3. The following nitrogenous bases are found in RNA: uracil, adenine, cytosine, guanine. 4. In eukaryotes the 5' end of the primary RNA transcript is modified. 5. If the sequence of the DNA template strand is 3'AAA TCG CCC 5', then the sequence of the RNA transcript is 5' UUU AGC GGG 3'.
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3) The protein secondary structure……… 1. known as an a helix is always found in an amphipathic form. 2. known as the b strand can form a sheet in both parallel and antiparallel orientations. 3. known as an a helix can be easily formed by an alternating series of proline and glycine amino acids. Which statement(s) is/are correct? 4) Which one of the following statements concerning DNA replication is correct? 5) DNA replication in E. coli requires a number of different enzymes and proteins. Which one of the following statements is correct? a. There are multiple origins of replication in E. coli. b. Duplex DNA is unwound by a helicase called DNA B. c. Binding proteins called replication factor A keep the unwound strands of DNA apart. d. DNA polymerase III synthesizes DNA starting at a DNA primer. e. DNA polymerase I joins two Okasaki fragments. 6) The replication of SV40 DNA has been studied in order to examine DNA replication in eukaryotes. Which one of the following statements concerning SV40 DNA replication is correct?