Chapter 9 Practice Quiz

Required information Why does each base in DNA have a complementary base? Complementary bases are a key feature of DNA structure. Adenine and thymine are complementary to one another as are guanine and cytosine. There are two important reasons why DNA is composed of complementary bases. The first is that only with complementary bases can the two strands of DNA have complementary sequences. Without the complementary sequences DNA replication as we know it would be impossible. The second reason is that the pairs of bases are complementary because their chemical structure allows for strong hydrogen bonding and they fit together well. The strong association between complementary bases makes DNA a stable molecule and aids in the detection of errors in DNA synthesis. View the animation below, then complete the quiz to test your knowledge of the concept. DNA replication is said to be a. dispersive b. semiconservative c. conservative d. liberal e. inconclusive

b. semiconservative

Required information Why does each base in DNA have a complementary base? Complementary bases are a key feature of DNA structure. Adenine and thymine are complementary to one another as are guanine and cytosine. There are two important reasons why DNA is composed of complementary bases. The first is that only with complementary bases can the two strands of DNA have complementary sequences. Without the complementary sequences DNA replication as we know it would be impossible. The second reason is that the pairs of bases are complementary because their chemical structure allows for strong hydrogen bonding and they fit together well. The strong association between complementary bases makes DNA a stable molecule and aids in the detection of errors in DNA synthesis. View the animation below, then complete the quiz to test your knowledge of the concept. Which of the following DNA sequences is complementary to 5' TAGAC 3'? a. 5' TAGAC 3' b. 5' ATCTG 3' c. 5' GTCTA 3' d. 5' CAGAT 3' e. None of these choices are correct.

c. 5' GTCTA 3'

Shown below is a representation of a centrifuge tube used in the Meselson-Stahl experiment. The positions where DNA of various strands would migrate are shown as horizontal lines. 'Heavy' is DNA in which all of the nitrogen is the heavy isotope (15N), 'Light' is DNA that consists of all light isotope of nitrogen (14N), and 'Half-heavy' is DNA in which some of the nitrogen is 14N and some of the nitrogen is 15N. Suppose that, as in the Meselson-Stahl experiment, E. coli is grown for many generations in heavy nitrogen (15N) precursors, then shifted to light nitrogen (14N) precursors for 1 or 2 generations. Select the test tube that best corresponds to the positions that DNA would be expected to migrate in the following hypothetical situations. (Not all letters may be used, and some may be used more than once.) 1. DNA replication is semiconservative, and the culture was grown in light media for 1 generation. 2. DNA replication is conservative, and the culture was grown in light media for 1 generation. 3. DNA replication is semiconservative, and the culture was grown in light media for 2 generations. 4. DNA replication is conservative, and the culture was grown in light media for 2 generations. 5. DNA replication is dispersive, and the culture was grown in light media for 1 generation. 6. DNA replication is semiconservative, and the culture was grown in light media for 1 generation, then shifted back to heavy media for 1 more generation. 7. Which tube represents the position expected if the bacteria were never shifted to light media at all?

1. B 2. A 3. C 4. A 5. B 6. D 7. E

Complete the sentences about the process of DNA replication with the correct terms. 1. DNA replication begins at an origin of replication, which expands to form two ____________ moving in opposite directions. 2. DNA double helix is separated into single strands by the enzyme ____________ . 3. Newly-exposed, unreplicated DNA is protected by ____________ . 4. Short segments of RNA, called ____________ are synthesized. 5. The enzyme that synthesizes the RNA primers is an RNA polymerase called ____________ . 6. The short RNA primers provide a free ____________ for replication. 7. New DNA is synthesized in the ____________ direction. 8. The enzyme that removes tightened coils ahead of the replication fork is ____________ . 9. The enzyme that catalyzes new DNA synthesis is ____________ . 10. DNA synthesis occurs continuously on the ____________ . 11. DNA synthesis occurs in small sections on the ____________ . 12. Fragments of discontinuous DNA synthesis are called ____________ . 13. Gaps in the sugar-phosphate backbone of DNA are closed by ____________ . a. DNA helicase b. lagging strand c. transfer RNA d. 3' to 5' e. leading strand f. RNA primers g. 3' OH h. single-stranded binding protein i. DNA ligase j. DNA polymerase k. 5' phosphate l. hexokinase m. topoisomerase n. 5' to 3' o. replication fork (s) p. Okazaki fragments q. ribosome r. primase

1. replication fork(s) 2. DNA helicase 3. single-strand binding protein 4. RNA primers 5. primase 6. 3' OH 7. 5' to 3' 8. topoisomerase 9. DNA polymerase 10. leading strand 11. lagging strand 12. Okazaki fragments 13. DNA ligase

Identify the sequence of eukaryotic chromosomal compaction by matching the descriptions with the correct steps in the process. a. wrapping of DNA around histone proteins b. Formation of a 30-nm fiber via histone H1 and other DNA-binding proteins c. Further compaction of radial loops to form heterochromatin d. metaphase chromosome with 2 copies of the DNA e. Formation of radial loop domains by anchoring the 30-nm fiber to protein fibers

1. wrapping of DNA around histone proteins 2. Formation of a 30-nm fiber via histone H1 and other DNA-binding proteins 3. Formation of radial loop domains by anchoring the 30-nm fiber to protein fibers 4. Further compaction of radial loops to form heterochromatin 5. metaphase chromosome with 2 copies of the DNA

The pairing of nitrogenous bases in DNA is specific because a. functional groups on each of the bases form hydrogen bonds with functional groups on only one other base. b. functional groups on each of the bases form covalent bonds with functional groups on only one other base. c. the pairing of DNA strands is antiparallel. d. the pairing of DNA strands is parallel. e. amino acids in the DNA form very specific three-dimensional shapes.

a. functional groups on each of the bases form hydrogen bonds with functional groups on only one other base.

Beginning with the simplest level of structure, put each level of organization of genetic material in order. a. nucleotide b. genome c. chromosome d. gene e. DNA

a. nucleotide d. gene e. DNA

Check All That Apply How is bacterial DNA replication similar to eukaryotic DNA replication? (Check all that apply.) a. Both bacterial and eukaryotic DNA replication have a single origin of replication. b. Both bacterial and eukaryotic DNA replication occur in a bidirectional manner. c. Both bacterial and eukaryotic DNA replication result in two DNA double helices that are both composed of one parental strand and one new strand. d. Both bacterial and eukaryotic DNA replication result in one DNA double helix that was the template and one completely new DNA double helix. e. Both bacterial and eukaryotic DNA replication use the same four nucleotides (A, C, G, and T).

b. Both bacterial and eukaryotic DNA replication occur in a bidirectional manner. c. Both bacterial and eukaryotic DNA replication result in two DNA double helices that are both composed of one parental strand and one new strand. d. Both bacterial and eukaryotic DNA replication result in one DNA double helix that was the template and one completely new DNA double helix.

Required information View the animation below, then complete the quiz to test your knowledge of the concept. How do DNA polymerase I and DNA Polymerase III differ? a. DNA polymerase I synthesizes DNA only on the leading strand and DNA polymerase III synthesize DNA only on the lagging strand. b. DNA polymerase III synthesizes DNA only on the leading strand and DNA polymerase I synthesize DNA only on the lagging strand. c. DNA polymerase III synthesizes the majority of the DNA, while DNA polymerase I synthesizes DNA in the regions where the RNA primers were laid down on the lagging strand. d. DNA polymerase III synthesizes the majority of the DNA, while DNA polymerase I synthesizes DNA in the regions where proofreading has found mismatched bases to occur. e. DNA polymerase III is the primary DNA polymerase in eukaryotes, while DNA polymerase I is the primary DNA polymerase in prokaryotes.

c. DNA polymerase III synthesizes the majority of the DNA, while DNA polymerase I synthesizes DNA in the regions where the RNA primers were laid down on the lagging strand.

Required information View the animation below, then complete the quiz to test your knowledge of the concept. A mutation results in the production of much less DNA ligase than normal. What would be a likely consequence? a. DNA replication would not be able to occur at all. b. DNA replication would occur, but the leading strand would be composed of many small fragments. c. DNA replication would occur, but replication of the lagging strand would take much longer than normal. d. DNA replication of both strands would occur slowly because the unwinding of DNA would be impaired.

c. DNA replication would occur, but replication of the lagging strand would take much longer than normal.

During the replication of a DNA molecule a. the two new products of replication will have different genetic information. b. A will be paired with G, and T will be paired with C. c. new base pairs must be formed according to Chargaff's rule. d. new base pairs arise by the formation of covalent bonds between the bases. e. the two strands in a parental molecule remain paired with each other.

c. new base pairs must be formed according to Chargaff's rule.

Required information Why does each base in DNA have a complementary base? Complementary bases are a key feature of DNA structure. Adenine and thymine are complementary to one another as are guanine and cytosine. There are two important reasons why DNA is composed of complementary bases. The first is that only with complementary bases can the two strands of DNA have complementary sequences. Without the complementary sequences DNA replication as we know it would be impossible. The second reason is that the pairs of bases are complementary because their chemical structure allows for strong hydrogen bonding and they fit together well. The strong association between complementary bases makes DNA a stable molecule and aids in the detection of errors in DNA synthesis. View the animation below, then complete the quiz to test your knowledge of the concept. DNA polymerase occasionally makes errors and adds an incorrect base. A new strand of DNA is being produced, and the template strand contains a G. Based on your knowledge of the structure of DNA, why is it more likely that DNA polymerase would accidently add a T to the new strand instead of a G or an A? a. Because G normally pairs with T. b. Because G normally pairs with either T or C. c. Because the structure of T and G are similar as they both have a double ring. d. Because the structure of T and C are similar as they both have a single ring.

d. Because the structure of T and C are similar as they both have a single ring.

Required information View the animation below, then complete the quiz to test your knowledge of the concept. The enzyme that travels along a template strand, assembling nucleotides into a growing DNA strand, is a. DNA polymerase I. b. DNA ligase. c. primase. d. DNA polymerase III. e. helicase.

d. DNA polymerase III.

Required information View the animation below, then complete the quiz to test your knowledge of the concept. Before DNA polymerase can begin assembling DNA nucleotides to produce either the Okazaki fragments of the lagging strand or the continuous molecule of the leading strand, which must occur? a. DNA polymerase III adds deoxyribonucleotides. b. DNA polymerase I removes some nucleotides and replaces them with DNA. c. Covalent bonds must be broken between the two strands of DNA. d. DNA ligase forms a covalent bond between two adjacent nucleotides in the same DNA strand. e. Primase constructs a short RNA primer.

e. Primase constructs a short RNA primer.

Which is NOT an essential property of the genetic material? a. The genetic material must contain information. b. The genetic material must be copied. c. The genetic material must be transmitted from parent to offspring. d. The genetic material must be variable, exhibiting differences between individuals and species. e. The genetic material must be a DNA double helix.

e. The genetic material must be a DNA double helix.

Required information View the animation below, then complete the quiz to test your knowledge of the concept. The enzyme that unwinds a segment of the DNA molecule is a. DNA polymerase. b. DNA ligase. c. Primase. d. DNA polymerase III. e. helicase.

e. helicase.