TEST BANK MICROBIOLOGY A Systems Approach 4TH EDITION COWAN

TEST BANK MICROBIOLOGY A Systems Approach 4TH EDITION COWAN

Chapter 09
Microbial Genetics

Multiple Choice Questions

1. Microorganisms exhibit genomes contained on
A. chromosomes.
B. plasmids.
C. mitochondrial DNA.
D. chloroplast DNA.
E. All of the choices are correct depending on the type of microorganism observed.

2. Eukaryotic chromosomes differ from prokaryotic chromosomes because only eukaryotes have
A. histone proteins.
B. chromosomes in a nucleus.
C. several to many chromosomes.
D. elongated, not circular, chromosomes.
E. All of the choices are correct.

3. Which of the following is not true of an organism’s genotype?
A. is inherited
B. are structural genes coding for proteins
C. are genes coding for RNA
D. are regulatory genes controlling gene expression
E. are the expressed traits governed by the genes

4. The _____ is all of the genetic material of a cell.
A. chromosome
B. plasmid
C. prophage
D. genome
E. proteome

5. A nucleosome is a linear chromosome wound around the
A. nuclear membrane.
B. rRNA.
C. mRNA.
D. histone.
E. nucleolus.

6. A _____ is a specific segment of DNA that codes for the production of one functional product.
A. intron
B. exon
C. gene
D. operator
E. triplet

7. The expression of genetic traits is referred to as the organism’s
A. genome.
B. genotype.
C. proteome.
D. phenotype.
E. proteotype.

8. The DNA of an organism is made up of subunits called
A. histones.
B. amino acids.
C. nucleotides.
D. mRNA.
E. polymerases.

9. Which is incorrect about purines?
A. only found in DNA, not in RNA
B. are nitrogenous bases
C. always paired with a specific pyrimidine
D. include adenine and guanine
E. found within nucleotides

10. The antiparallel arrangement within DNA molecules refers to
A. each base bonding at the 1′ position of the sugar.
B. a purine always bonding to a pyrimidine.
C. one helix strand that runs from the 5′ to 3′ direction and the other strand runs from the 3′ to 5′ direction.
D. an original parent DNA strand and one newly synthesized DNA strand comprising a new DNA molecule.

11. All of the following pertain to nitrogenous bases except
A. form pairs by hydrogen bonding.
B. guanine pairs with uracil.
C. adenine pairs with thymine.
D. cytosine and thymine are pyrimidines.
E. allows variation from one nucleotide to another which creates the encoded information.

12. Each nucleotide is composed of
A. one phosphate, one nitrogenous base, and one sugar.
B. one phosphate, one nitrogenous base, and two sugars.
C. two phosphates, one nitrogenous base, and one sugar.
D. two phosphates, one nitrogenous base, and two sugars.
E. one phosphate, two nitrogenous bases, and one sugar.

13. Base pairs in DNA are held together by _____ bonds.
A. peptide
B. nonpolar covalent
C. polar covalent
D. hydrogen
E. sulfhydryl

14. The duplication of a cell’s DNA is called
A. mitosis.
B. replication.
C. transcription.
D. translation.
E. mutation.

15. Structural genes code for
A. ribosomal RNA molecules.
B. transfer RNA molecules.
C. cellular proteins.
D. gene expression elements.

16. During replication, each parent DNA strand serves as a _____ for synthesis of new DNA strands.
A. copy point
B. template
C. comparison molecule
D. scaffold
E. reservoir

17. Semiconservative replication refers to
A. each base bonding at the 1′ position of the sugar.
B. a purine always bonding to a pyrimidine.
C. one helix strand that runs from the 5′ to 3′ direction and the other strand that runs from the 3′ to 5′ direction.
D. an original parent DNA strand and one newly synthesized DNA strand comprising a new DNA molecule.

18. DNA polymerase III
A. is needed for adding nucleotides during mRNA synthesis.
B. synthesizes new DNA only in the 5′ to 3′ direction.
C. cannot add nucleotides to the lagging strand.
D. synthesizes an RNA primer.

19. Okazaki fragments are attached to the growing end of the lagging strand by
A. DNA ligase.
B. DNA polymerase.
C. DNA helicase.
D. DNA gyrase.
E. primase.

20. The enzyme that helps pack DNA into the cell by coiling the DNA into a tight bundle is
A. DNA ligase.
B. DNA polymerase.
C. DNA helicase.
D. DNA gyrase.
E. primase.

21. The enzyme that can proofread replicating DNA, detect incorrect bases, excise them, and correctly replace them is
A. DNA ligase.
B. DNA polymerase.
C. DNA helicase.
D. DNA gyrase.
E. primase.

22. The site where the old DNA strands separate and new DNA strands will be synthesized is called the
A. primer.
B. Okazaki fragment.
C. template.
D. rolling circle.
E. replication fork.

23. DNA gyrase
A. unwinds DNA.
B. supercoils DNA.
C. cleaves DNA.
D. joins free DNA ends.

24. Helicase
A. unwinds DNA.
B. supercoils DNA.
C. unwinds RNA.
D. winds RNA.

25. DNA Polymerase I
A. removes primers.
B. adds bases to new DNA chain.
C. seals DNA gaps.
D. proofreads DNA chain.

26. DNA Polymerase III
A. synthesizes primer.
B. removes primer.
C. joins Okazaki fragments.
D. unzips the DNA helix.
E. proofreads new DNA.

27. A permanent, inheritable change in the genetic information is called a/n
A. translation.
B. transcription.
C. mutation.
D. alteration.
E. regeneration.

28. Replication of DNA begins at a/n ___ rich area.
A. guanine-cytosine
B. uracil-adenine
C. adenine-thymine
D. adenine-cytosine
E. guanine-adenine

29. A primer comprised of ____ is needed at the origin of nucleotide addition.
A. polymerase III
B. polymerase I
C. helicase
D. RNA
E. DNA

30. Groups of three consecutive bases along the DNA of a gene have the code for one
A. protein.
B. nucleotide.
C. amino acid.
D. purine.

31. The three-base sequence on DNA that codes for an amino acid is called a/n
A. codon.
B. exon.
C. anticodon.
D. intron.
E. triplet.

32. The RNA molecules that carry amino acids to the ribosomes during protein synthesis are called
A. ribosomal RNA.
B. messenger RNA.
C. transfer RNA.
D. primer RNA.
E. ribozymes.

33. This molecule is translated into an amino acid sequence:
A. ribosomal RNA
B. messenger RNA
C. transfer RNA
D. primer RNA
E. ribozymes

34. RNA molecules differ from DNA molecules because only RNA
A. has ribose.
B. has uracil.
C. is typically one strand of nucleotides.
D. does not have thymine.
E. All of the choices are correct.

35. Which of the following is not a type of microRNA?
A. tRNA
B. miRNA
C. antisense RNA
D. riboswitch
E. siRNA

36. All of the following pertain to transcription except
A. occurs on a ribosome in the cytoplasm.
B. occurs before translation.
C. requires RNA polymerase.
D. requires a template DNA strand.
E. a process used in the synthesis of protein.

37. The nontranscribed region of DNA to which RNA polymerase binds to initiate transcription is called the
A. promoter.
B. operator.
C. operon.
D. exon.
E. intron.

38. RNA polymerase binds to the
A. start codon.
B. termination sequence.
C. regulation sequence.
D. promoter sequence.

39. Which of the following is incorrect about transfer RNA?
A. has a bottom hairpin loop with an anticodon
B. has an anticodon that is complementary to a codon
C. contains a binding site for an amino acid
D. the initiator tRNA that binds to the P site has the anticodon UAC
E. initiator tRNA in bacteria carries tryptophan

40. If a codon for alanine is GCA, then the anticodon is
A. GCA.
B. CGT.
C. ACG.
D. CGU.
E. UGC.

41. The following pertain to ribosomes during protein synthesis except
A. contain codons within their rRNA molecules.
B. participate only in translation.
C. bind to the 5′ end of mRNA by their small subunit.
D. use their large subunit to supply enzymes for peptide bonding.
E. shift towards the 3′ direction along the mRNA strand from one codon to the next.

42. Which of the following is incorrect about termination codons?
A. are also called nonsense codons
B. where the bond between the final tRNA and the polymerase is broken
C. include AUG
D. include UAA, UAG, and UGA
E. do not have corresponding tRNA

43. Which of the following is not associated with a prokaryotic ribosome?
A. has a 70s subunit
B. has a peptide (P) site
C. has an exit site
D. small unit provides the enzymes for making peptide bonds
E. has an amino acid (A) site

44. A sequence of bases within a gene that does not code for protein is called a/n
A. promoter.
B. operator.
C. operon.
D. exon.
E. intron.

45. Split genes
A. are common in prokaryotes and eukaryotes.
B. only have exons initially transcribed to mRNA.
C. have introns located only at the beginning and end of a coding region.
D. are acted upon by spliceosomes to excise introns and then join exons.

46. Which is incorrect about inducible operons?
A. have genes turned off by a buildup of end product
B. are often for use in catabolic pathways
C. are normally turned off
D. are turned on by the substrate of the enzyme
E. include the lac operon

47. The operon segment composed of the gene that codes for a protein repressor is called the
A. operator.
B. structural locus.
C. regulator.
D. promoter.

48. Synthesis of an inducible enzyme requires
A. repressor alone bound to operator.
B. substrate bound to repressor.
C. substrate bound to promoter.
D. corepressor and repressor binding to operator.

49. Synthesis of a repressible enzyme is inhibited by
A. repressor alone bound to operator.
B. substrate bound to repressor.
C. substrate bound to promoter.
D. corepressor and repressor binding to operator.

50. Full induction of the lactose operon requires
A. lactose present.
B. lactose and glucose present.
C. lactose present without glucose.
D. lactose and arabinose present.

51. The lactose repressor
A. is transcribed with the structural lac genes.
B. is activated by binding lactose.
C. is inactivated by binding lactose.
D. requires lactose for its transcription.

52. Gene regulation can involve a protein repressor that blocks _____ from initiating transcription.
A. DNA polymerase I
B. DNA polymerase III
C. RNA polymerase
D. mRNA
E. rRNA

53. Repressible operons require that _____ binds to the repressor protein before it can bind to the operator.
A. the product
B. a cofactor
C. a coenzyme
D. the substrate
E. the reactant

54. A mutation that changes a normal codon to a stop codon is called a ___ mutation.
A. point
B. silent
C. back
D. missense
E. nonsense

55. The most serious type of mutation is a ___ mutation.
A. point
B. silent
C. frameshift
D. back

56. If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATA ETH EBI GRA T?
A. missense
B. nonsense
C. insertion
D. deletion
E. silent

57. If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE THE BAG RAT?
A. point
B. nonsense
C. insertion
D. deletion
E. silent

58. If the wild type DNA sequence reads THE CAT ATE THE BIG RAT, what type of mutation would change the sequence to THE CAT ATE (stop)?
A. missense
B. nonsense
C. insertion
D. deletion
E. silent

59. A frameshift is caused by ______ mutations.
A. missense and insertion
B. missense and nonsense
C. nonsense and deletion
D. deletion and insertion
E. insertion and nonsense

60. What type of mutation alters the base but not the amino acid being coded for?
A. silent
B. back
C. point
D. nonsense
E. missense

61. A screening system called the _____ test is used for detecting chemicals with carcinogenic potential.
A. Koch
B. Ames
C. mutation
D. cancer
E. Iowa

62. The process in which mutations are removed and the correct bases added is called
A. transduction.
B. excision repair.
C. frameshift.
D. back-mutation.
E. transformation.

63. Bacterial conjugation involves
A. bacteriophage carrying donor DNA to the recipient cell.
B. a donor cell with a plasmid that synthesizes a pilus.
C. naked DNA fragments from a lysed donor cell taken up by a recipient cell.
D. new progeny cells with genes from two parent bacterial cells.

64. Which cell can transfer the most DNA?
A. F+ cell
B. F- cell
C. Hfr cell
D. R cell
E. B cell

65. Which of the following is not a type of bacterial DNA recombination?
A. transformation
B. conjugation
C. mitosis
D. transduction

66. Which of the following is not true of conjugation?
A. involves direct contact between cells
B. transfers genes for drug resistance
C. transfers genes for enzymes and adherence molecules
D. involves the action of bacteriophage
E. the donor retains a copy of the transferred genes

67. Hfr transfer involves all of the following except
A. gene integration into the bacterial chromosome.
B. plasmid gene transfer.
C. F factor is part of the F+ donor chromosome.
D. high frequency transfer.
E. a pilus connection between F+ and F- cells.

68. The transfer of DNA fragments from a dead cell to a live, competent recipient cell that results in a changed recipient cell is termed
A. transduction.
B. conjugation.
C. transformation.
D. transmission.
E. mitosis.

69. The development of virulent, toxin-producing bacterial strains due to the presence of a temperate phage can occur through the process of:
A. bacterial conjugation.
B. transformation.
C. generalized transduction.
D. specialized transduction.

70. A bacteriophage transfers a random fragment of DNA of the previous host to the current host. This is an example of
A. conjugation.
B. generalized transduction.
C. specialized transduction.
D. creation of an Hfr cell.

71. The jumping of a gene from one location to another is done by
A. conjugation.
B. transposons.
C. transformation.
D. transduction.
E. transmission.

72. Which of the following is not true of transposons?
A. can change pigmentation
B. can replace damaged DNA
C. can transfer drug resistance
D. can change the genome
E. are always part of plasmids

73. Which of the following additions have been made to principles of the central dogma of biology?
A. DNA information cannot be converted into RNA information.
B. Protein information can be converted into DNA information.
C. RNA can be used to regulate gene function.
D. DNA codes for proteins.

74. In Griffith’s experiments with Streptococcus pneumoniae, rough nonencapsulated Streptococci were converted into smooth encapsulated Streptococci in the presence of the heat-killed smooth encapsulated Streptococci. Which microbial process had Griffith identified?
A. transduction
B. conjugation
C. transformation
D. cloning

75. Of the following list, which antibiotics affect protein synthesis?
A. penicillin
B. tetracycline
C. chloramphenicol
D. ciprofloxacin
E. Both tetracycline and chloramphenicol are correct.

True / False Questions
76. The smallest unit of heredity is a chromosome.

77. DNA polymerase can only add new nucleotides to the 3′ DNA end of the template.

78. DNA replication proceeds in one direction around the bacterial chromosome.

79. Transcription occurs within the nucleus or at the nucleoid.

80. In bacteria, initiator tRNA carries formyl methionine.

81. Introns have no detectable functions.

82. Excised introns form structures called lariats.

83. Lactose is a corepressor in the lac operon.

84. Repressible operons are normally turned on in the cell.

85. Induced mutations result from errors in DNA replication.

86. DNA photolyase, in the presence of visible light, can repair DNA damage due to ultraviolet radiation.

87. All mutations are not beneficial to the cell.

Multiple Choice Questions

88. An unidentified cell was found to contain introns and exons, to express DNA polymerase and RNA polymerase. Although it exhibits a promoter region it has no operons. You conclude that this cell:
A. is eukaryotic.
B. is prokaryotic.
C. is either a prokaryotic or eukaryotic cell.
D. is actually a virus.

89. Looking at your results of the Ames test, using bacteriological agar medium plates lacking the amino acid histidine, you find that there are many colonies growing on the agar. Your interpretation of this result is:
A. the bacterium has turned its operon genes on, producing proteins necessary for growth.
B. the chemical being tested is mutagenic.
C. the bacterium does not have any plasmids, so it cannot grow on the medium.
D. the drug being tested has no inhibitory effect on the bacterium, therefore it is not a good antibiotic to give for treatment of disease.

90. A mutation has occurred during DNA replication while the cell was preparing to divide. As a result of this, the codon ACU of mRNA has now become ACC. Interestingly, there is no change to the protein being made. Why not?
A. This is a silent mutation.
B. The original amino acid isoleucine was changed to leucine, but they are the same variation of amino acid so no change to the protein.
C. The mutation was fixed, and even though the codon is now ACC the correct amino acid is put into place for the normal protein.
D. This is not a mutation that causes a big change, so there is no change to the protein being made.

True / False Questions

91. A bacterial cell has replicated its plasmid, and when this cell divides into 2 daughter cells, each cell receives one copy of the plasmid. This is an example of horizontal gene transfer.

Multiple Choice Questions

92. You have taken E. coli strain A, which has its own plasmids, and mixed it with E. coli B strain without plasmids. E. coli B cells now have plasmids but, in addition, they also carry some genes from E. coli A strain. What has happened is:
A. the E. coli B cells have become mutants of the original culture.
B. vertical transmission of DNA has occurred.
C. an example of transformation.
D. the cells of E. coli A were Hfr cells.