1. True or False? At the DNA level, recombination is initiated by a single stranded break in a DNA molecule. False 2. True or False? Dideoxy sequencing is a chain initiation method of DNA sequencing. False 3. True or False? New polynucleotide strands are initiated by a primosome containing RNA polymerase that synthesizes a short RNA primer complementary to a region of the template strand. True 4. True or False? The major DNA polymerase has a 5' to 3' polymerase function that serves for proofreading. False 5. True or False? The currently favored model for homologous recombination is the double strand break and repair model. True 6. Which enzyme catalyzes the elongation of a DNA strand in the 5' to 3' direction? A. primase B. DNA ligase C. DNA polymerase D. topoisomerase E. helicase 7. The chemical bonds in DNA by which the sugar components of adjacent nucleotides are linked are called A. hydrogene bonds. B. peptide bonds. C. phosphodiester bonds. 9. Who demonstrated that DNA undergoes semiconservative replication? A. James Watson and Francis Crick B. Rosalind Franklin and Maurice Wilkins C. Mathew Meselson and Franklin Stahl D. Max Gilbert and Fredrick Sanger E. Alfred Hershey and Martha Chase 10. In DNA replication, primase is responsible for A. removal of a terminal nucleotide in a polynucleotide chain. B. connecting two fragments of DNA together. C. cutting DNA at a site specific sequence. D. producing Okazaki fragments. E. synthesizing an RNA primer for DNA synthesis. 11. In a replicating DNA molecule, the region in which parental strands are separating and new strands are being synthesized is called a Page 1
A. Okazaki fragment. B. primer. C. replication fork. D. heteroduplex. 12. Discontinuous replication refers to the fact that A. DNA synthesis begins at multiple origins of replication. B. one of the daughter strands of a replicated piece of DNA is made in short fragments that are joined together. C. DNA synthesis is not continuous with RNA synthesis. D. DNA synthesis starts and stops many times before completed. 13. In DNA replication, RNA primer is necessary because A. DNA synthesis starts and stops many times before completed. B. DNA synthesis begins at multiple origins of replication. C. the two strands of a replicating helix must make a full rotation to unwind. D. DNA polymerase is unable to initiate a new polynucleotide chain. 14. A DNA molecule or a region of DNA that replicates as an individual unit is known as a A. primer. B. Okazaki fragment. C. replicon. D. replication fork. 15. DNA synthesis proceeds by the elongation of primer chains, always in the A. 5' to 3' direction. B. 3' to 5' direction. C. 5' to 5' direction. D. 3' to 3' direction. 16. The mode of DNA replication in which a circular parent molecule produces a linear branch of newly formed DNA is called A. rolling circle replication. B. q replication. C. discontinuous replication. 17. Dideoxyribose is chemically different from deoxyribose in that it A. lacks a 3' OH group. B. lacks a 5' P group. C. contains an extra 3' OH group. D. has fewer carbons in the sugar ring. Page 2
18. An exonuclease is an enzyme that can A. remove a terminal nucleotide in a polynucleotide chain. B. connect two fragments of DNA together. C. cut DNA at a site specific sequence. D. catalyze DNA synthesis. E. produce an RNA primer for DNA synthesis. 19. In DNA replication, the lagging strand is A. the single DNA strand that is synthesized as a continuous unit. B. a single DNA strand synthesized in short fragments that are ultimately joined together. C. single stranded RNA primers used in DNA synthesis. D. the template strand from which the new strand is synthesized. E. None of the above. 20. In DNA replication, the leading strand is A. the single DNA strand that is synthesized as a continuous unit. B. a single DNA strand synthesized in short fragments that are ultimately joined together. C. single stranded RNA primers used in DNA synthesis. D. the template strand from which the new strand is synthesized. E. None of the above. 21. Unwinding the double helix to separate the parental strands requires a A. primase. B. DNA ligase. C. DNA polymerase. D. topoisomerase. E. helicase. 22. DNA ligase functions to A. catalyze the formation of hydrogen bonds between adjacent 5' P and 3' OH termini. B. relax supercoiling of DNA. C. add methyl groups to DNA. D. facilitate base pairing between single stranded molecules of DNA. E. catalyze the formation of covalent bonds between adjacent 5' P and 3' OH termini. 23. Replication of the eukaryotic chromosome is initiated at A. single site. B. two sites. C. 10 sites. D. multiple sites. 24. Replication of the E. coli chromosome is initiated at Page 3
A. a single site. B. two sites. C. 10 sites. D. multiple sites. 25. Gene conversion results from A. discontinuous replication. B. photoreactivation. C. mismatch repair. D. SOS repair. E. excision repair. 26. This enzyme cleaves both strands of DNA, swivels the ends of the broken strands to relieve the torsional stress, and then rejoins the strands. A. gyrase B. ligase C. ribonuclease D. catalase E. helicase 29. The presence of a primer with a free 3' OH group is essential for DNA polymerase to synthesize DNA since no known DNA polymerase is able to initiate chains. 30. In a replicating DNA molecule, the region in which parental strands are separating and new strands are being synthesized is called a replication fork. 31. The RNA polymerase that produces the primer necessary for DNA synthesis is called the primase. 35. The position along a molecule at which DNA replication begins is called the origin of replication. 36. Unwinding the double helix to separate the parental strands requires a helicase protein that hydrolyzes ATP to drive the unwinding reaction. 37. The short fragments in which the lagging strand is synthesized are known as Okazaki fragments. 38. Equilibrium density gradient centrifugation is a technique that uses CsCl to separate DNA molecules. 39. Replication is semiconservative in that each parental single strand, which serves as a template strand, is found in one of the double stranded progeny molecules. 40. The chemical bonds in DNA by which the sugar components of adjacent nucleotides are linked through the phosphate groups are called phosphodiester bonds. 41. Dideoxynucleotides contain the sugar dideoxyribose which lacks the 3 OH, which is essential for attachment of the next nucleotide in a growing DNA strand. Page 4
44. When the products of a meiotic division in a Aa heterozygous genotype are in some other ratio than the expected 1A:1a, they are said to result from gene conversion. 45. Gene conversion results from a normal DNA repair process in the cell known as mismatch repair. 46. The term massive parallel sequencing refers to machines that can sequence millions of templates simultaneously. Page 5