*

Avery and his coworkers showed that the agent responsible for changing nonvirulent bacteria into virulent bacteria was
A. protein.
B. polysaccharide.
C. DNA.
D. RNA.
E. lipid.

*DNA

*

Which statement about the Hershey-Chase experiment is false?
A. DNA was labeled with radioactive phosphorus.
B. Protein was labeled with radioactive sulfur.
C. The virus-infected bacteria contained radioactive phosphorus.
D. The virus-infected bacteria contained radioactive sulfur.

*The virus-infected bacteria contained radioactive sulfur.

*

As the two strands of DNA are unraveled, which enzyme relieves the strain on the two strands so you don't produce supercoiled DNA?
A. DNA polymerase
B. DNA ligase
C. DNA gyrase
D. DNA endonuclease
E. DNA exonuclease

*DNA gyrate

*Chargaff's rules for the pairing of nitrogen bases is
A. A = C and G = T.
B. A = T and G = C.
C. A = G and C = T.
D. A+T = G+C.

*B. A = T and G = C

*Information obtained by Franklin from X-ray crystallography on DNA suggested that it is shaped like a
A. helix.
B. ribbon.
C. hollow cylinder.
D. pleated sheet.
E. icosahedron.

*helix

*If a short sequence of DNA is 5' AATTGCCGT 3', its complement is
A. 5' AAAACGCCA 3'.
B. 3' TTAACGGCT 5'.
C. 3' TTAACGGCA 5'.
D. 3' TTAAGCCGA 5'.
E. 5' TTAAAGGCA 3'.

*D. 3' TTAAGCCGA 5'.

*During DNA replication, which enzyme removes the RNA primers and then fills in the gap?
A. DNA pol I
B. DNA primase
C. DNA pol III
D. DNA ligase

*DNA pol 1

1. Viruses that attack bacteria are called
A. phages
B. proviruses
C. virulent
D. lytic

phages

2. ___ is the genetic material for all cellular organisms and some viruses.
A. RNA
B. DNA
C. Protein
D. Chromatin

DNA

3. Nucleotides have a phosphate group attached at the ___ carbon atom of the sugar.
A. 2'
B. 3'
C. 5'
D. 1'

5'

7. DNA consists of two antiparallel strands of nucleotides held together by
A. peptide bonds.
B. covalent bonds.
C. ionic bonds.
D. hydrogen bonds.

hydrogen bonds

8. The method of DNA replication, where each original strand is used as a template to build a new strand, is called the
A. conservative method.
B. semiconservative method.
C. disruptive method.
D. continuous method.
E. replication and amplification method.

semiconservative method

10. Who originally discovered the process of bacterial transformation?
A. Watson and Crick
B. Chargaff
C. Hershey and Chase
D. Griffith
E. Meselson and Stahl

griffith

11. When a mixture of live nonvirulent bacteria and dead virulent bacteria was injected into mice, Griffith unexpectedly found that the injected mice died. He explained this result by suggesting that the nonvirulent bacteria are being
A. activated.
B. transformed.
C. translated.
D. transcribed.
E. expressed.

transformed

13. Which statement about the Hershey-Chase experiment is false?
A. DNA was labeled with radioactive phosphorus.
B. Protein was labeled with radioactive sulfur.
C. The virus-infected bacteria contained radioactive phosphorus.
D. The virus-infected bacteria contained radioactive sulfur.

D. The virus-infected bacteria contained radioactive sulfur.

14. Based on their experiment with T2 bacteriophages, Hershey and Chase concluded that
A. DNA replication is semiconservative.
B. the phage coat contains the genetic material.
C. DNA functions as the genetic material.
D. A always pairs with T and G always pairs with C.
E. virulent bacteria can transform nonvirulent bacteria.

C. DNA functions as the genetic material.

15. After attaching to a bacterial cell, a bacteriophage typically
A. injects protein into the cell.
B. extracts protein from the cell.
C. injects DNA into the cell.
D. extracts DNA from the cell.
E. transforms the cell into a virulent strain.

injects DNA into the cell

16. DNA primase
A. creates a short RNA primer that is complementary to an RNA template.
B. creates a short DNA primer that is complementary to an RNA template.
C. creates a short DNA primer that is complementary to a DNA template.
D. creates a short DNA template that is complementary to an RNA primer.
E. creates a short RNA primer that is complementary to a DNA template.

E. creates a short RNA primer that is complementary to a DNA template.

18. Which is not a component of nucleic acids?
A. organic nitrogenous base
B. pentose sugar
C. phosphate
D. sulfur

sulfur

19. The chemical bond connecting one nucleotide with the next along one strand of a DNA molecule is called a
A. glycosidic bond.
B. hydrogen bond.
C. phosphate bond.
D. phosphodiester bond.
E. peptide bond.

D. phosphodiester bond.

20. Chargaff's rules for the pairing of nitrogen bases is
A. A = C and G = T.
B. A = T and G = C.
C. A = G and C = T.
D. A+T = G+C.

B. A = T and G = C.

21. Information obtained by Franklin from X-ray crystallography on DNA suggested that it is shaped like a
A. helix.
B. ribbon.
C. hollow cylinder.
D. pleated sheet.
E. icosahedron.

helix

23. The two strands of a DNA molecule contain nitrogen bases which are
A. identical.
B. parallel.
C. complementary.
D. proportionate.
E. random.

complementary

24. Replication of DNA is
A. conservative.
B. redundant.
C. dispersive.
D. semiconservative.
E. semidispersive.

semiconservative

25. During DNA replication, each new strand begins with a short
A. amino acid primer.
B. lipid primer.
C. hydrophilic primer.
D. DNA primer.
E. RNA primer.

RNA primer

26. The lagging strand is replicated with a series of Okazaki fragments and that is why its synthesis is considered to be
A. discontinuous.
B. continuous.
C. bidirectional.
D. antiparallel.
E. semiconservative.

discontinuous

27. DNA replication always proceeds by adding new bases to the _______ end of an existing strand.
A. 1'
B. 2'
C. 3'
D. 4'
E. 5'

3'

28. Which of the following statements about DNA replication false?
A. The two strands are separated.
B. Each existing strand is used as a template for making a new strand.
C. Synthesis of both new strands is in the 5' to 3' direction.
D. The newly synthesized DNA is packaged into one nucleus, and the original DNA is packaged into another nucleus.

D. The newly synthesized DNA is packaged into one nucleus, and the original DNA is packaged into another nucleus.

29. The double helix model of DNA structure was proposed by
A. Watson and Crick.
B. Griffith.
C. Avery.
D. Franklin.
E. Chargaff.

watson and crick

30. Griffith, a British microbiologist, used bacteria and mice to demonstrate the process of transformation. During transformation,
A. a bacterial chromosome produces an exact copy of itself.
B. the nucleus of a mouse cell repairs itself when damaged by bacterial infection.
C. DNA from an infected mouse cell changes bacteria from a non-pathogenic to a pathogenic form.
D. genetic material is transferred from one bacterial cell to another.
E. a bacterial cell is transformed into a spore during unsuitable environmental conditions.

D. genetic material is transferred from one bacterial cell to another.

31. In 1952, Hershey and Chase confirmed Avery's (1944) conclusion that
A. proteins are the repositories for hereditary information.
B. DNA is the repository for hereditary information.
C. RNA is the repository for hereditary information.
D. each DNA molecule is composed of two strands that are twisted into a double helix.
E. the replication of DNA is semiconservative

B. DNA is the repository for hereditary information.

32. If 14% of the nucleotides from a DNA molecule contain the base T, what percent will contain the base G?
A. 14%
B. 18%
C. 28%
D. 36%
E. 72%

36%

34. After DNA replication is complete, each strand of the original molecule is bound to a new complementary strand. This process is known as
A. disruptive replication.
B. conservative replication.
C. semiconservative replication.
D. dispersive replication.
E. stabilizing replication.

C. semiconservative replication.

35. The site where the two original DNA strands separate and active replication occurs is called the
A. replication folk.
B. replisome.
C. primosome.
D. lagging strand.
E. sliding clamp subunit.

a replication fork

36. The replisome has two main subcomponents. They are
A. the replication folk and the sliding clamp subunit.
B. the primosome and the sliding clamp subunit.
C. the replication folk and the DNA pol III enzymes.
D. the DNA pol III enzymes and the sliding clamp subunits.
E. the primosome and the DNA pol III enzymes.

E. the primosome and the DNA pol III enzymes.

37. During replication, which enzyme unwinds the DNA double helix?
A. DNA primase
B. DNA polymerase I
C. DNA helicase
D. DNA gyrase
E. DNA ligase

DNA helices

38. What is the correct sequence for DNA replication in E. coli?
A. initiation, termination, elongation
B. initiation, elongation, termination
C. elongation, termination, initiation
D. elongation, initiation, termination

B. initiation, elongation, termination

39. Eukaryotic organisms speed up the process of DNA replication by
A. shortening the initiation phase.
B. producing several sliding clamp complexes which provide more binding sites for DNA pol III.
C. using DNA gyrase to unravel the double helix rather than DNA helicase.
D. using multiple origins of replication on each chromosome.

D. using multiple origins of replication on each chromosome.

40. Endonucleases and exonucleases are enzymes that can remove nucleotides from a polynucleotide chain. An endonuclease removes nucleotides _______ while an exonuclease removes nucleotides _____________.
A. from the 5' end of the chain; from the 3' end of the chain
B. from the 3' end of the chain; from the 5' end of the chain
C. internally; from the ends of the chain
D. from the ends of the chain; internally

C. internally; from the ends of the chain

41. During DNA replication, DNA pol III synthesizes the lagging strand in segments, called
A. replication fragments.
B. Chargaff's segments.
C. repeating primers.
D. replisomes.
E. Okazaki fragments.

E. Okazaki fragments.

42. Who proposed that the structure of DNA is a double helix with two polynucleotide chains running in opposite directions and held together by hydrogen bonding between pairs of nitrogenous bases?
A. Hershey and Chase
B. Chargaff
C. Franklin
D. Watson and Crick
E. Meselson and Stahl

D. Watson and Crick

43. Who demonstrated that phage genetic material is DNA and not protein?
A. Hershey and Chase
B. Chargaff
C. Franklin
D. Watson and Crick
E. Avery, MacLeod, and McCarty

A. Hershey and Chase

44. Who provided X-ray diffraction photographs of purified DNA fibers that suggested a helical structure with a consistent diameter of about 2 nm and a complete helical turn every 3.4 nm?
A. Hershey and Chase
B. Chargaff
C. Franklin
D. Watson and Crick

franklin

45. Who proposed that in any DNA molecule, A =T and G = C?
A. Hershey and Chase
B. Chargaff
C. Franklin
D. Watson and Crick

char gaff

46. In Griffith's experiments,
A. mice infected with live nonvirulent bacteria developed pneumonia and died.
B. nonvirulent bacteria transformed the virulent bacteria into a nonvirulent variety.
C. mice infected with heat-killed virulent bacteria and live nonvirulent bacteria developed pneumonia and died.
D. mice infected with heat-killed virulent bacteria and heat-killed nonvirulent bacteria developed pneumonia and died.

C. mice infected with heat-killed virulent bacteria and live nonvirulent bacteria developed pneumonia and died.

47. Avery, MacLeod, and McCarty's experiments revealed that the transforming principle had all of the following properties except
A. its activity was destroyed by treatment with proteases.
B. its activity was unaffected by RNA-digesting enzymes.
C. its activity was unaffected by lipid extraction.
D. its activity was destroyed by treatment with DNA endonucleases.

A. its activity was destroyed by treatment with proteases.

48. If we think of the DNA double helix as a twisted ladder, what makes up the rungs or steps of the ladder?
A. phosphate groups only
B. alternating phosphate groups and sugars
C. sugars only
D. purines and pyrimidines
E. phosphate groups and bases

D. purines and pyrimidines

49. Deoxyribose has a carbon atom that is not part of the pentose ring. In a nucleotide, what is attached to this carbon?
A. a nitrogenous base
B. a phosphate group
C. three hydrogen atoms
D. one hydrogen atom

B. a phosphate group

50. Which of the following DNA sequences is complementary to 5' ATGGTCAGT 3'?
A. 5' ATGGTCAGT 3'
B. 5' TGACTGGTA 3'
C. 5' TACCAGTCA 3'
D. 5' ACTGACCAT 3'

D. 5' ACTGACCAT 3'

51. In DNA, a purine must always pair with a pyrimidine and vice versa in order to ensure that
A. the distance between the two phosphodiester backbones remains constant.
B. the two strands are antiparallel.
C. the distance between one base pair and the next remains constant.
D. each base pair is held together by three hydrogen bonds.

A. the distance between the two phosphodiester backbones remains constant.

52. During DNA replication, which enzyme removes the RNA primers and then fills in the gap?
A. DNA pol I
B. DNA primase
C. DNA pol III
D. DNA ligase

A. DNA pol I

53. If a mutation prevented synthesis of the beta subunit of DNA pol III, which would be most affected?
A. DNA unwinding
B. formation of RNA primers
C. formation of the replication fork
D. processivity
E. removal of RNA primers

D. processivity

54. Why does DNA pol I carry the number one?
A. It was the first polymerase isolated from E. coli.
B. It is the first polymerase to be activated during DNA replication.
C. It is the only polymerase that has both 3' to 5' and 5' to 3' exonuclease activity.
D. It is the smallest polymerase.

A. It was the first polymerase isolated from E. coli.

55. You are asked to give a classroom demonstration of DNA supercoiling. To do so, you take two different colored pieces of rubber tubing, twist them very tightly and excessively around each other and join the ends of the tubing appropriately. Next, you relieve the supercoiling by breaking one strand and unwinding it. In this demonstration, the breaking and unwinding to relieve the supercoiling simulates the action of
A. exonucleases.
B. polymerases.
C. ligases.
D. topoisomerases.
E. primases.

D. topoisomerases.

56. In which cells would you expect to find the highest level of telomerase?
A. muscle cells
B. oocytes
C. neurons
D. cells that replenish the lining of the gut

D. cells that replenish the lining of the gut

57. You are asked to participate in a clinical trial for a new drug that can activate telomerase. Which of the following is a likely risk of such a drug?
A. decreased capacity for tissue repair
B. increased vulnerability to cancer
C. premature aging
D. decreased telomere length

B. increased vulnerability to cancer

58. After a long week of sunbathing on the beach, what type of DNA damage should you be most concerned about?
A. photolyase-induced mutations
B. decreased telomere length
C. thymine dimers
D. activation of uvr A, B, and C genes

C. thymine dimers

59. Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder. Patients with XP exhibit a cellular hypersensitivity to ultraviolet (UV) radiation, a high incidence of skin cancer and premature aging. Based on these clinical characteristics, what is the most likely cause for this disease?
A. defects in DNA repair
B. defects in DNA replication
C. lack of telomerase activity
D. shortened telomeres

A. defects in DNA repair

60. If a mutation produced helicase that was unable to hydrolyze ATP, DNA replication would be
A. slowed down.
B. stopped.
C. speeded up.
D. unaffected.
E. more prone to errors.

stopped?/slowed down

61. Suppose a new form of DNA pol III is discovered that does not require a primer to begin synthesis of a new strand. All other properties of the enzyme remain unchanged. In order to completely replicate all chromosomes in a eukaryotic cell that uses this new enzyme, which of the following would no longer be necessary?
A. Okazaki fragments
B. telomeres
C. DNA ligase
D. DNA helicase
E. the replisome

okazaki fragments

62. Suppose a new species of bacterium is discovered. It contains a form of DNA pol III that can add new nucleotides to either the 5' end or the 3' end of an existing strand. All other properties of the enzyme remain unchanged. How would DNA replication in these bacteria differ from normal replication?
A. both new strands could be synthesized continuously
B. both new strands could be synthesized discontinuously
C. DNA pol I would no longer be required for replication
D. DNA ligase would no longer be required for replication

A. both new strands could be synthesized continuously

63. If 16% of the nucleotides in one strand of a DNA molecule contain the base G, what percent of the nucleotides on the complementary strand will also contain the base G?
A. 16%
B. 8%
C. 34%
D. 32%
E. Impossible to determine from the information given.

E. Impossible to determine from the information given.

64. You decide to repeat the Meselson-Stahl experiment, except this time you plan to grow the cells on light 14N medium for many generations and then transfer them to heavy 15N medium and allow them to grow for 2 additional generations (2 rounds of DNA replication). If the conservative model of DNA replication is correct, what is the expected distribution of DNA in the density gradient after one round of replication?
A. One band of intermediate density
B. One band of light density
C. One band of heavy density
D. One band of light density and one band of heavy density
E. One band of light density and one band of intermediate density

D. One band of light density and one band of heavy density

65. You decide to repeat the Meselson-Stahl experiment, except this time you plan to grow the cells on light 14N medium for many generations and then transfer them to heavy 15N medium and allow them to grow for 2 additional generations (2 rounds of DNA replication). If the semiconservative model of DNA replication is correct, what is the expected distribution of DNA in the density gradient after two rounds of replication?
A. One band of intermediate density
B. One band of intermediate density and one band of light density
C. One band of intermediate density and one band of heavy density
D. One band of heavy density and one band of light density
E. One band of heavy density

C. One band of intermediate density and one band of heavy density

67. Genetic analysis indicates that an unknown organism contains a gene that codes for a defective form of telomerase. Based on this information alone, you can conclude that this organism
A. is prokaryotic.
B. is eukaryotic.
C. has unusually long telomeres.
D. has an increased risk of developing cancer.

B. is eukaryotic.

68. Genetic analysis indicates that you have a gene that codes for a defective form of photolyase. This puts you at increased risk for developing
A. skin cancer.
B. lung cancer.
C. colon cancer.
D. heart disease.
E. kidney stones.

skin cancer