Biology- Chapter 16

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Biology- Chapter 16
2014-11-09 09:19:37
Principles Biology

Principles of Biology- Chapter 16
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  1. In his transformation experiments, what did Griffith observe?
    Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form
  2. How do we describe transformation in bacteria?
    Assimilation of external DNA into a cell
  3. After mixing a heat-killed, phosphorescent strain of bacteria with a living nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observations would provide the best evidence that the ability to fluoresce is a heritable trait?
    Descendants of the living cells are also phosphorescent
  4. In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?
    DNA contains phosphorus, whereas protein does not
  5. Which of the following investigators was/were responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.
    Erwin Chargaff
  6. Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA?
    The diameter of the helix
  7. It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following?
    Sequence of bases
  8. In an analysis of the nucleotide composition of DNA, which of the following will be found?
    A+C= G+T
  9. Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons?
    Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many
  10. What is meant by the description "antiparallel" regarding the strands that make up DNA?
    The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand
  11. Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
    DNA in both daughter cells would be radioactive
  12. An Okazaki fragment has which of the following arrangements?
    5' RNA nucleotides, DNA nucleotide 3'
  13. In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?
    No replication fork will be formed
  14. Which enzyme catalyzes the elongation of a DNA strand in the 5'-3' direction?
    DNA polymerase III
  15. Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?
    Gaps left at the 5' end of the lagging strand
  16. The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?
    Adding numerous short DNA sequences such as TTAGGG, which form a hairpin turn
  17. The DNA of telomeres has been found to be highly conserved throughout the evolution of eukaryotes. What does this most probably reflect?
    That the critical function of telomeres must be maintained
  18. An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?
  19. Polytene chromosomes of Drosophila salivary glands each consist of multiple identical DNA strands that are aligned in parallel arrays. How could these arise?
    Replication without separation
  20. To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?
    Endonuclease, DNA polymerase I, DNA ligase
  21. What is the function of DNA polymerase III?
    To add nucleotides to the 3' end of a growing DNA strand
  22. The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that
    The nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose
  23. The leading and the lagging strands differ in that
    The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction
  24. A new DNA strand elongates only in the 5' to 3' direction because
    DNA polymerase can only add nucleotides to the free 3' end
  25. What is the function of topoisomerase?
    Relieving strain in the DNA ahead of the replication fork
  26. What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
    It joins Okazaki fragments together
  27. Which of the following help(s) to hold the DNA strands apart while they are being replicated?
    Single-strand binding proteins
  28. Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way?
    They cannot repair thymine dimers
  29. Which of the following would you expect of a eukaryote lacking telomerase?
    A reduction in chromosome length in gametes
  30. Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?
    DNA polymerase I
  31. Which of the enzymes separates the DNA strands during replication?
  32. Which of the enzymes covalently connects segments of DNA?
  33. Which of the enzymes synthesized short segments of RNA?
  34. Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?
    Double-stranded DNA, four kinds of dNTPs, primers, origins
  35. Studies of nucleosomes have shown that histones (except H1) exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?
    The two types of tetramers associate to form an octamer
  36. In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding?
    The 30-nm chromatin fiber
  37. Which of the following statements describes the eukaryotic chromosome?
    It consists of a single linear molecule of double-stranded DNA plus protein
  38. If a cell were unable to produce histone proteins, which of the following would be a likely effect?
    The cell's DNA couldn't be packed into its nucleus
  39. Which of the following statements is true of histones?
    Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together
  40. Why do histones bind tightly to DNA?
    Histones are positively charged, and DNA is negatively charged
  41. Which of the following represents the order of increasingly higher levels of organization of chromatin?
    Nucleosome, 30-nm chromatin fiber, looped domain
  42. Which of the following statements describe chromatin?
    Heterochromatin is highly condensed, whereas euchromatin is less compact
  43. In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (16N) and then transferred them to a medium containing 14N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of 14N?
  44. A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 16N medium for several generations and then transfer them to 14N medium. Which pattern in the figure above would you expect if the DNA was replicated in a conservative manner?
  45. Once the pattern found after one round of replication was observed, Meselson and Stahl could be confident of which of the following conclusions?
    Replication is not conservative
  46. Grains represent radioactive material within the replicating eye
    There are two replication forks going in opposite directions
  47. Why won't this experiment work?
    Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would nit distinguish between DNA and proteins
  48. These two classes of DNA probably represent
    Leading strands and Okazaki fragments
  49. In his work with pneumonia-causing bacteria and mice, Griffith found that
    Some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic
  50. What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?
    DNA polymerase can join new nucleotides only to the 3' end of a growing strand
  51. In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?
  52. The elongation of the leading strand during DNA synthesis
    Depends on the action of DNA polymerase
  53. In a nucleosome, the DNA is wrapped around
  54. What density distribution of DNA would you expect in this experiment?
    One low-density and one intermediate-density band
  55. What has she probably left out of the mixture?
    DNA ligase
  56. What combination of proteins could repair such damage?
    Nuclease, DNA polymerase, DNA ligase