Download 011 Chapter 11 Microbial Genetics: Gene Structure Replication amp

011 Chapter 11 Microbial Genetics: Gene Structure Replication amp Expression
1. Which of the following nitrogenous bases is usually found in RNA but not in DNA?
A. adenine
B. thymine
C. uracil
D. guanine
2. Which of the following is true about the structure of DNA?
A. Purine and pyrimidine bases are attached to the 1'-carbon of the deoxyribose sugars.
B. Purine and pyrimidine bases partition away from the aqueous solvent and are found within the
cylinder formed by the two intertwined nucleotide chains.
C. Adjacent bases are stacked on top of each other in planes that are almost perpendicular to the
long axis of the double helix.
D. all of the choices
3. Procaryotic DNA replication occurs at a rate of
A. 750–1,000 base pairs per second.
B. 750–1,000 base pairs per minute.
C. 50–100 base pairs per second.
D. 50–100 base pairs per minute.
4. In which of the following types of procaryotes have split genes been found?
A. bacteria
B. cyanobacteria
C. Archaea
D. bacteria and Archaea
E. cyanobacteria and Archaea
5. The genetic code was deciphered in the 1960s in large part by the efforts of
A. Avery and Griffith.
B. Khorana and Nirenberg.
C. Watson and Crick.
D. Hershey and Chase.
6. Over twisting or under twisting of double helical DNA generates
A. hypertwists.
B. hypotwists.
C. hypercoils.
D. supercoils.
7. During replication the 2 strands of the DNA molecule are unwound from one another by
enzymes called
A. ligases.
B. unwindases.
C. helicases.
D. primases.
8. The Y-shaped part of the DNA molecule where the actual replication process occurs is called
the replication __________.
A. tongue
B. fork
C. junction
D. splice
9. Each chromosome has one or more __________ site(s) where replication begins.
A. promoter
B. replicon
C. origin
D. bifurcate
10. In eucaryotic chromosomes, the DNA is organized into __________ in which the DNA is
twisted around small basic proteins that are rich in the amino acids lysine and arginine.
A. nucleosomes
B. replisomes
C. dictyosomes
D. mesosomes
11. Chromosomes of most bacteria are comprised of
A. double-stranded circles of DNA.
B. double-stranded linear molecules.
C. single-stranded circular molecules.
D. single-stranded linear molecules.
12. When a DNA molecule is replicated, the daughter molecules contain one strand of parental
DNA and one strand of newly synthesized DNA; this is called __________ replication.
A. hemiconservative
B. conservative
C. semiconservative
D. dispersive
13. The double helical structure of DNA was proposed by
A. Messelsohn and Stahl.
B. Avery, McCarty, and MacLeod.
C. Hershey and Chase.
D. Watson and Crick.
14. Which of the following is not a complementary base pair usually found in DNA molecules?
A. adenine-thymine
B. guanine-cytosine
C. adenine-uracil
D. all of the choices
15. Which of the following is not a pyrimidine?
A. adenine
B. cytosine
C. thymine
D. uracil
16. The coding sequence in the DNA of __________ is normally continuous; that is, it is not
interrupted by noncoding sequences.
A. procaryotes
B. plants
C. mammals
D. most insects
17. Key sequences exist within promoters, which vary somewhat among various promoters but
are sufficiently constant that they can be represented by a sequence of bases most often found at
each position. These representations are called __________ sequences.
A. convergence
B. idealized
C. consensus
D. common
18. Which of the following is not considered the final product of the expression of a gene?
A. a polypeptide chain
B. an mRNA molecule
C. a tRNA molecule
D. an rRNA molecule
19. The transcribed, but not translated, sequence that is immediately upstream of the region and
encodes the functional product is called the __________ region.
A. leader
B. promoter
C. coding
D. trailer
20. The region at which the RNA polymerase binds is the __________ region.
A. leader
B. promoter
C. coding
D. trailer
21. The transcribed and translated region of a gene is the __________ region.
A. leader
B. promoter
C. coding
D. trailer
22. The principle of transformation was first demonstrated by which of the following individuals
or groups of individuals?
A. Avery, MacLeod, and McCarty
B. Griffith
C. Hershey and Chase
D. Watson and Crick
23. Which of the following individuals or groups of individuals demonstrated that the
transforming principle was DNA?
A. Avery, MacLeod, and McCarty
B. Griffith
C. Hershey and Chase
D. Watson and Crick
24. The genetic code is said to be __________ because more than one codon will specify a
particular amino acid.
A. ambiguous
B. degenerate
C. multiplicative
D. repetitious
25. Which of the following is in the coding region of a gene?
A. promoter
B. leader
C. trailer
D. none of the choices
26. Which of the following is not a termination codon?
A. AUG
B. UAA
C. UAG
D. UGA
27. Which of the following is the initiator codon?
A. AUG
B. UAA
C. UAG
D. UGA
28. The genetic code is translated in groups of __________ bases
A. two
B. three
C. four
D. five
29. ________ RNA molecules deliver amino acids to ribosomes during translation.
A. Messenger RNA (mRNA)
B. Transfer RNA (tRNA)
C. Ribosomal RNA (rRNA)
D. Heterogeneous nuclear RNA (hnRNA)
30. The energy needed for protein synthesis is provided by the hydrolysis of
A. ATP.
B. GTP.
C. UTP.
D. ATP and GTP.
E. ATP and UTP.
31. The portion of the tRNA molecule that binds to the codon on the mRNA is called the
A. c-codon.
B. anticodon.
C. complementary codon.
D. paracodon.
32. How many different termination codons are used in translation?
A. one
B. two
C. three
D. four
33. What is the minimum number of aminoacyl-tRNA synthetase enzymes needed to attach
amino acids to all the various tRNA molecules?
A. 20
B. 61
C. 64
D. as many as there are different tRNAs
34. In __________ ribosomes can attach to the mRNA and begin translation even though
transcription has not been completed.
A. procaryotes
B. eucaryotes
C. fungi
D. protozoa and some plants
35. In eucaryotes a series of __________ residues are added to the 3' end of an RNA molecule as
part of the posttranscriptional processing used to produce functional mRNA.
A. adenine
B. guanine
C. cytosine
D. uracil
36. Ribosomes consist of __________ separate subunits that come together as part of the
initiation process and dissociate immediately after termination.
A. two
B. three
C. four
D. five
37. The __________ reaction sequentially links adjacent amino acids into the growing
polypeptide chain.
A. dipeptidation
B. transpeptidation
C. peptidation
D. propeptidation
38. A complex consisting of a single mRNA molecule with several ribosomes is called a
A. polysome.
B. multisome.
C. maxisome.
D. none of the choices
39. The unexpressed regions of split genes are called
A. exons.
B. endons.
C. introns.
D. codons.
40. The expressed regions of split genes are called
A. exons.
B. endons.
C. introns.
D. codons.
41. A bacterial __________ is the nontranscribed region of the DNA to which RNA polymerase
binds in order to initiate transcription.
A. operon
B. operator
C. promoter
D. initiator
42. A large RNA molecule that is produced by transcription and must be processed to produce
smaller mRNA molecules is called
A. premessenger RNA (pmRNA).
B. transfer RNA (tRNA).
C. ribosomal RNA (rRNA).
D. heterogeneous nuclear RNA (hnRNA).
43. A section of DNA that codes for a protein or other functional product is called a(n)
A. codon.
B. gene.
C. replicon.
D. anticodon.
44. The strand of DNA for a particular gene that is copied by the RNA polymerase to form
mRNA is called the __________ strand.
A. leading
B. template
C. transcription
D. copy
45. In order to add a single amino acid to a growing polypeptide chain, a grand total of
__________ molecules or ATP or GTP are utilized.
A. two
B. three
C. four
D. six
46. The process by which the base sequence of all or a portion of a DNA molecule is used to
direct the synthesis of an RNA molecule is called
A. replication.
B. transcription.
C. reverse transcription.
D. translation.
47. The process by which the base sequence of an RNA molecule is used to direct the synthesis
of a protein is called
A. replication.
B. transcription.
C. reverse transcription.
D. translation.
48. When RNA polymerase catalyzes the addition of a nucleotide to a growing mRNA chain, a
byproduct of this reaction is
A. phosphate.
B. pyrophosphate.
C. orthophosphate.
D. water.
49. The Pribnow box of E. coli
A. is centered approximately 35 bp upstream of the start site of transcription
B. is centered between 7 and 13 bp upstream of the start codon
C. is centered approximately 10 bp upstream of the start site of transcription
D. is located at the site of addition of poly (A) in eucaryotic mRNAs
50. RNA polymerase II of eucaryotes is responsible for transcribing
A. rRNA.
B. snRNA.
C. tRNA.
D. hnRNA.
51. RNA polymerase III of eucaryotes is responsible for transcribing
A. 28S rRNA.
B. snRNA.
C. tRNA.
D. hnRNA.
52. Posttranscriptional modifications that yield eucaryotic mRNAs include which of the
following?
A. splicing to remove introns
B. 5' poly (A) tracts
C. 3' caps
D. all of the choices
53. Bacterial chromosomes, unlike eucaryotic chromosomes, often consist of a single replicon.
True False
54. Cellular RNA molecules are always initially single stranded, but they often have double
stranded regions because of internal base pairing.
True False
55. Split genes have been found in both procaryotes and eucaryotes but are much more common
in eucaryotes.
True False
56. The basic differences between RNA and DNA reside in their sugar and pyrimidine bases;
RNA has ribose and uracil whereas DNA has deoxyribose and thymine.
True False
57. Because of its larger size, the replication rate of eucaryotic genomes is significantly faster
than the replication rate of procaryotic genomes.
True False
58. DNA replication is a complex process, and as a result the frequency of error is quite high.
True False
59. The DNA of bacteria, like that of eucaryotes, is associated with basic proteins known as
histones.
True False
60. A B-type DNA double helix contains a wider major groove and a narrower minor groove
because the two polynucleotide strands are not positioned directly opposite one another in the
helical cylinder.
True False
61. The terminator codons are translated codons; that is, they specify amino acids to be inserted
into the last position of a growing polypeptide chain.
True False
62. For most genes, coding information is found in both strands.
True False
63. All genes on the same DNA molecule use the same strand of DNA for their coding
information.
True False
64. The genetic code is usually translated in a nonoverlapping fashion.
True False
65. The protein coding sequences in interrupted genes are called exons.
True False
66. The noncoding sequences located between the start codon and the stop codon in interrupted
genes are called introns.
True False
67. Eucaryotic genes are frequently interrupted. Interesting exceptions are the genes for histones
which contain no introns.
True False
68. Eucaryotic mRNAs are modified by addition of a poly(A) sequences at the 3' end and 7methyl guanosine at the 5' end.
True False
69. Split genes are more commonly observed in eucaryotes than in procaryotes.
True False
70. Some microbial proteins are spliced after translation in a reaction that results in removal of
one or more internal intervening sequences called inteins.
True False
71. After a protein has been synthesized, the formyl group is cleaved from the initial methionine;
therefore, the first amino acid in all proteins of procaryotes is methionine.
True False
72. Procaryotes initiate the synthesis of all proteins with formylmethionine.
True False
73. Initiation of translation in eucaryotes is similar to that in procaryotes except that more
initiation factors are required in eucaryotes.
True False
74. The two strands of a DNA molecule are __________; that is, they are oriented in opposite
directions.
75. 166 base pairs of eucaryotic DNA coiled around a complex of 8 histones is called a
_______________.
76. The basic proteins that associate with and condense eucaryotic DNA are called __________.
77. In procaryotes there is evidence that the replication fork is initially formed after binding of
the __________ protein.
78. Hershey and Chase demonstrated that when the bacteriophage T2 infected its host cell, the
__________ is injected into the host but the __________ remained outside.
79. The __________ describes the specific set of genes an organism possesses.
80. The __________ is the collection of characteristics of an organism that an investigator
observes.
81. As procaryotes normally only have one set of genes, they are called __________.
82. A consensus sequence in the untranslated leader sequence of a procaryotic mRNA which
serves as a ribosome binding site is called the _____ - _____ sequence.
83. RNA molecules that catalyze the removal of their own introns are called ________.
84. In eucaryotes a so-called cap consisting of __________ is attached to the 5' end of the
molecule during posttranscriptional modification of hnRNA to produce functional mRNA.
85. Proteins that recognize unfolded polypeptides and help them fold into their proper
conformations are called ______________.
86. Messenger RNA molecules that direct the synthesis of more than one polypeptide are said to
be __________.
87. mRNA molecules have a nontranslated sequence called the __________ , which is located
downstream of the termination codon.
88. Aminoacyl-tRNA synthetases catalyze covalent addition of __________ __________ to
tRNAs.
89. On mRNA molecules, a nontranslated sequence called the ___________ usually precedes the
initiation codon.
90. Posttranscriptional modifications of heterogeneous nuclear RNA molecules yield
_________.
91. Splicing of eucaryotic heteronuclear RNA is catalyzed by ______________.
012 Chapter 12 Microbial Genetics: Regulation of Gene Expression
1. Which of the following is not a mechanism for the regulation of enzyme synthesis?
A. induction
B. repression
C. end product inhibition
D. attenuation
2. The initial substrate of a(n) __________ pathway usually serves as the inducer for the
expression of the genes of that pathway.
A. catabolic
B. anabolic
C. metabolic
D. parabolic
3. The site on the DNA to which a repressor protein binds is the __________.
A. operon
B. operator
C. promoter
D. regulator
4. When bound to the DNA, the repressor protein usually prevents attachment of the RNA
polymerase to the __________.
A. operon
B. operator
C. promoter
D. regulator
5. What term describes a set of genes that are coordinately regulated together under the control
of a single promoter?
A. codon
B. regulon
C. transcription
D. operon
6. In some circumstances, when two different carbon sources are available, growth will occur
first using one carbon source, then after a short lag period, growth will resume using the second
carbon source. This process is called __________ growth.
A. biphasic
B. bimorphic
C. diauxic
D. dimorphic
7. Attenuation requires tight coupling between transcription and translation and, therefore, occurs
in
A. eucaryotes.
B. procaryotes.
C. fungi and plants.
D. eucaryotes and procaryotes
8. Which of the following is not a regulatory mechanism used to control the lactose operon in
Escherichia coli?
A. induction
B. catabolite repression
C. attenuation
D. all of the choices
9. Which of the following is not a regulatory mechanism used to control the tryptophan operon in
Escherichia coli?
A. repression
B. catabolite repression
C. attenuation
D. all of the choices
10. Enzymes that are expressed at a constant level all the time are said to be:
A. inducible.
B. repressible.
C. constitutive.
D. attenuated.
11. When a repressor binds to the operator site on the DNA it normally
A. inhibits the initiation of transcription.
B. reduces the rate of transcription.
C. terminates transcription that has already been initiated.
D. has no effect on transcription.
12. Attenuation is used to control transcription of some __________ pathways involved in amino
acid biosynthesis.
A. catabolic
B. anabolic
C. metabolic
D. parabolic
13. __________ alter repressor proteins thereby increasing the rate of transcription initiation.
A. Inducers
B. Corepressors
C. Effectors
D. Modulators
14. __________ activate repressor proteins thereby decreasing the synthesis of certain enzymes.
A. Inducers
B. Corepressors
C. Effectors
D. Modulators
15. The __________ is a rho-independent termination site found in the leader region of certain
operons, which, under the influence of ribosome behavior, controls the continued transcription of
that operon.
A. modulator
B. operator
C. attenuator
D. terminator
16. If Escherichia coli is cultured in broth containing both glucose and lactose, it
A. uses glucose preferentially until the supply is exhausted, then uses lactose.
B. uses lactose preferentially until the supply is exhausted, then uses glucose.
C. uses glucose and lactose simultaneously.
D. uses only the glucose (it cannot use lactose as a source of carbon).
17. Regulation of gene expression serves to do all of the following except
A. conserve energy and raw materials
B. maintain balance between the amounts of various cell proteins
C. adjust the activity of existing proteins in the cell
D. adapt to long-term environmental change
18. The presence of histones does not affect gene expression in
A. eucaryotes
B. archaea
C. bacteria
D. archaea and bacteria
19. So-called two-component regulatory systems
A. include a sensor kinase and a response regulator.
B. play a key role in regulating sporulation in Bacillus.
C. play a key role in regulating the OmpF and OmpC porin proteins in E. coli.
D. all of the choices
20. The E. coli lac operon has ________ operator sequences.
A. one
B. two
C. three
D. four
21. The activity of adenyl cyclase is influenced by
A. the phosphotransferase system
B. the presence of lactose in the environment
C. homoserine lactones
D. none of the choices
22. The sensor kinase for the OmpF: OmpC two-component regulatory system is
A. the OmpK protein.
B. the EnvZ protein.
C. the MicF RNA.
D. none of the choices.
23. What is the key factor determining whether or not attenuation will occur when transcription
of the E. coli trp operon has been initiated?
A. the activity level of adenyl cyclase
B. the trp operon repressor
C. the level of tryptophan in the environment
D. the level of trp-tRNA that is charged with tryptophan
24. While standard two-component regulatory systems typically act to control gene transcription,
phosphorelay systems can act either to control gene transcription or to control
A. translation
B. protein activity
C. DNA replication
D. all of the choices
25. If the E. coli trp operon leader peptide is being translated to completion very rapidly
A. the 1:2 pause loop and the 3:4 terminator loop will form
B. only the 1:2 pause loop will form
C. only the 2:3 anti-terminator loop will form
D. only the 3:4 terminator loop will form
26. The terminator versus anti-terminator function of the T box-based riboswitch used by Grampositive bacteria to regulate amino acid-related genes is determined by
A. the binding of the appropriate uncharged tRNA
B. the rate of leader peptide synthesis
C. the binding of the T box binding protein
D. the utilization of the appropriate sigma factor by RNA polymerase
27. Riboswitches that can block the initiation of translation because of a conformational change
that occurs in the leader sequence of an mRNA when the appropriate regulatory effector binds
the mRNA achieve that blockage of translation initiation by the sequestering of
A. the promoter
B. the attenuator
C. the Shine-Delgarno sequence
D. the AUG start codon
28. An operon network that is under the control of a common regulatory protein while each
operon is still also under the control of its own unique regulatory protein is most specifically
referred to as a
A. regulon.
B. webulon.
C. modulon.
D. complexon.
29. The standard or housekeeping sigma factor used most often by E. coli RNA polymerase
under normal growth conditions is called sigma ___.
A. 70
B. 32
C. S
D. E
30. Acyl homoserine lactones used in quorum sensing regulate their own synthesis by a(n)
____________ system.
A. riboswitch
B. antisense
C. catabolite repression
D. autoinduction
31. During sporulation in Bacillus subtilis, the response regulator that positively controls many
genes needed for sporulation and negatively controls genes not needed during sporulation is
A. SpoOB
B. SpoOA
C. SpoOF
D. SpoOC
32. During the early stages of sporulation in Bacillus subtilis, ________ is active in the forespore
and ________ is active in the mother cell.
A. E; F
B. K; F
C. F; K
D. F; E
33. During sporulation in Bacillus subtilis, inactive precursor forms of new sigma factors are
activated at the appropriate time by
A. proteolysis
B. phosphorylation
C. RNA binding
D. chaperone re-folding
34. In eucaryotes, some small RNAs are important structural components of the
A. ribosome.
B. endoplasmic reticulum.
C. spliceosome.
D. eucaryotes do not utilize small RNAs.
35. The sensing of starvation that leads to sporulation in Bacillus subtilis is accomplished by
a(n)
A. small RNA.
B. sensor kinase.
C. response regulator.
D. quorum regulatory effector.
36. Different species of LuxS-producing bacteria can interfere with each others communication
by ________________ specific quorum sensing molecules.
A. degrading
B. modifying
C. over producing
D. none of the choices
37. Cell-to-cell communication by quorum sensing has been shown to be important in the
regulation of genes needed for
A. virulence.
B. biofilm production.
C. plasmid transfer.
D. all of the choices.
38. When the Catabolite Activator Protein binds to its binding site in DNA, it
A. displaces repressors.
B. bends the DNA.
C. promotes the assembly of other transcription factors at the promoter.
D. eliminates the need for a sigma factor on the part of RNA polymerase
39. Most E. coli antisense RNAs work with the a protein called ______ to regulate their target
mRNAs.
A. CAP
B. MicF
C. Hfq
D. none of the choices
40. In two component regulatory systems, the response regulator typically receives a
____________ from the sensor kinase when it has been activated.
A. pyruvate
B. phosphate
C. acetyl group
D. methyl group
41. With the E. coli trp operon where both repression and attenuation occur, the extent of
regulation achieved by repression is _____________ the extent of regulation achieved by
attenuation.
A. the same as
B. less than
C. greater than
D. repression is not used in the regulation of the E. coli trp operon
42. The enzymes required for the utilization of a particular energy source are usually produced
regardless of the availability of the energy source.
True False
43. If a particular end product is already present in abundant amounts in the environment, cells
will usually not continue to produce enzymes whose sole purpose is to manufacture more of that
end product.
True False
44. In the presence of both glucose and lactose, the lactose repressor is not bound to the operator
and the genes of the lactose operon are expressed.
True False
45. One way to regulate gene expression is through the production of different sigma factors.
These cause RNA polymerase to bind to different sets of promoters, thereby altering the pattern
of gene expression.
True False
46. The real inducer for the E. coli lac operon is allolactose produced by the action of permease
on lactose.
True False
47. Two-component signal transduction systems are found in the Archaea and the Bacteria, but
not in Eucarya.
True False
48. The binding of arabinose to the AraC protein allows it to form a loop in the DNA upstream
of the ara operon promoter.
True False
49. Small RNAs that regulate translation by binding to the leader region of mRNAs are called
antisense RNAs.
True False
50. The regulation of gene expression in the Archaea is totally different than the regulation of
gene expression in Bacteria.
True False
51. Gene regulation during sporulation in Bacillus subtilis involves BOTH temporal and spatial
control.
True False
52. In anabolic pathways, the end product often functions as a __________.
53. If a set of genes is induced in the presence of the controlling substance, it is referred to as
__________ control.
54. If a set of genes is repressed in the presence of the controlling substance, it is referred to as
__________ control.
55. In order for high level expression of the E. coli lac operon to occur, a complex of catabolite
activator protein and __________ must be bound to the DNA near the promoter.
56. When there is no arabinose available in the environment, the AraC protein acts as a(n)
______________ for the E. coli ara operon.
57. When arabinose is present in the environment, the AraC protein acts as a(n)
______________ for the E. coli ara operon.
58. A collection of genes or operons controlled by a common regulatory protein is called a(n)
___________ .
59. In eucaryotes, transcription factors that function as activators bind regulatory sites called
_____________.
60. In eucaryotes, transcription factors that function as repressors bind regulatory sites called
_____________.
013 Chapter 13 Microbial Genetics: Mechanisms of Genetic Variation
1. The process of combining genetic material from two organisms to generate a chromosome
with a nucleotide sequence that is different from either parent is called
A. transformation.
B. conjugation.
C. recombination.
D. transduction.
2. A reciprocal exchange in which a pair of very similar sequences break and rejoin in a
crossover is called __________ recombination.
A. homologous
B. site-specific
C. replicative
D. none of the choices
3. Site-specific recombination systems
A. do not depend on extensive nucleotide sequence homology.
B. depend on specialized recombinases that are different for each system.
C. are features of some viruses.
D. All of the choices are true.
4. The incorporation of a single strand of donor DNA into a recipient DNA duplex so that the
donor strand replaces one of the strands or the recipient duplex generates __________ DNA.
A. aberrant
B. unstable
C. heterogeneous
D. heteroduplex
5. DNA molecules that enter a bacterium by one of several mechanisms is called a(n)
A. merozygote.
B. exogenote.
C. endogenote.
D. none of the choices
6. The genome of a recipient cell is called a(n) __________.
A. merozygote
B. exogenote
C. endogenote
D. none of the choices
7. A recipient cell that is temporarily diploid for a portion of the genome during the replacement
process is called a(n) __________.
A. merozygote
B. exogenote
C. endogenote
D. none of the choices
8. Plasmids that have genes for resistance to antibiotics are called __________ factors.
A. col
B. resistance
C. virulence
D. metabolic
9. Which of the following is not true about transposable elements?
A. They move about the chromosomes within an organism.
B. They lack the infectious cycle of temperate phages.
C. They reproduce as independent replicons like plasmids.
D. All of these are true about transposable elements.
10. Which of the following effects may be mediated by transposable elements?
A. insertional mutagenesis
B. activation of nearby genes
C. formation of genetic deletions
D. all of the choices
11. In an F+  F- conjugation, the donor is the __________ strain.
A. F+
B. FC. both F+ and F- (It is a reciprocal exchange)
D. neither F+ nor F- (There is no exchange)
12. After an F+  F- mating, the donor is __________ and the recipient is __________.
A. F+; FB. F-; F+
C. F-; FD. F+; F+
13. In which of the following matings does conjugal DNA transfer happen?
A. F+  F+
B. Hfr  Hfr
C. Hfr  F+
D. none of the choices
14. When an F plasmid integrates into the host chromosome, the strain is referred to as
A. F+.
B. Hfr.
C. F'.
D. F-.
15. Which of the following best represents the order of gene transfer in an Hfr  F- mating?
A. all plasmid genes followed by some or all of the chromosome
B. part of the plasmid followed by the chromosome followed by the rest of the plasmid
C. the chromosome followed by the plasmid
D. part of the chromosome followed by the plasmid followed by the rest of the chromosome
16. Complete transfer in an Hfr  F- mating takes approximately __________ minutes.
A. 20
B. 50
C. 100
D. 200
17. An F' plasmid results when
A. an F+  F- mating is interrupted before completion.
B. an Hfr  F- mating is interrupted before completion.
C. an integrated F plasmid is incorrectly excised, bringing host genes with it.
D. none of the choices
18. Conjugative transposons
A. can be transferred from one bacterium to another by a phage mediated process
B. may be involved in the spread of antibiotic resistance in bacteria
C. often express enzymes that degrade aromatic compounds
D. all of the choices
19. When an F' plasmid acts as the donor in a mating, which of the following do(es) not happen?
A. The recipient becomes F'.
B. The plasmid is transferred, including the chromosomal genes now on the plasmid.
C. Some chromosomal genes not on the plasmid are transferred.
D. all of the choices
20. Insertion sequences are
A. normally relatively short (700 to 1,600 bp).
B. capable of transposition.
C. are discrete genetic elements with direct repeats at their ends.
D. normally relatively short (700 to 1,600 bp) and capable of transposition.
E. all of the choices
21. When a recipient cell acquires a piece of naked DNA from the environment, it is called
A. conjugation.
B. transformation.
C. transduction.
D. transfection.
22. When bacterial genes are transferred to another bacterium by a virus, it is called
A. conjugation.
B. transformation.
C. transduction.
D. transfection.
23. Which of the following occurs with generalized transduction?
A. degradation of the host chromosome into randomly sized fragments
B. packaging of any DNA fragment of the appropriate size
C. transfer of any bacterial gene to the subsequent host
D. All of these occur with generalized transduction.
24. Which of the following is not true of specialized transduction?
A. It is carried out by temperate phage.
B. It is restricted to those genes on either side of an integrated prophage.
C. The phage genome retains the full complement of phage genes.
D. All of these are true of specialized transduction.
25. The mechanism that transfers the most DNA between E. coli cells is
A. generalized transduction.
B. transformation.
C. Hfr  F- conjugation.
D. transposition.
26. Who is credited with demonstrating polar and non-reciprocal transfer of DNA between two
mating E. coli cells?
A. Hayes
B. Lederberg
C. Tatum
D. none of the choices
27. Transfer of genetic information via direct cell-cell contact is called
A. transformation.
B. transduction.
C. transfection.
D. conjugation.
28. Specialized transduction can be carried out by
A. any bacteriophage.
B. any temperate bacteriophage.
C. only those temperate bacteriophages that integrate into the host chromosome.
D. all of the choices
29. When DNA from a wild type phage is annealed to that of a mutant phage which carries a
deletion or insertion, one or more single stranded loops may form. The position of these loops
can be used to map mutations using a method called _______________ mapping.
A. denaturation
B. heteroduplex
C. restriction endonuclease
D. hybridoma
30. Which of the following is true of the integration of a viral genome into the host
chromosome?
A. It is a form of site-specific recombination.
B. The enzymes are specific for the virus and its host.
C. Integration begins the process of host chromosome degradation.
D. It is a form of site-specific recombination and the enzymes are specific for the virus and its
host
31. Which of the following is a possible fate for an exogenote?
A. integration into the host chromosome
B. independent replication and functioning
C. degradation to nucleotides
D. all of the choices
32. Which of these transposable elements do not carry genes for functions other than those
needed for transposition?
A. insertion sequences
B. composite transposons
C. retrotransposons
D. conjugal transposons
33. Transposons that transpose by inserting a copy at a new location while a copy remains at the
original location are said to transpose by _______________ transposition.
A. simple
B. composite
C. incomplete
D. replicative
34. Transfer of genes from one mature independent organism to another is called
A. horizontal gene transfer.
B. lateral gene transfer.
C. vertical gene transfer.
D. orthogonal gene transfer.
35. Alternate forms of genes resulting from mutations are called
A. isoforms.
B. alterons.
C. alleles.
D. lethal.
36. SOS repair
A. requires RecA protein.
B. is inducible by DNA damage.
C. is error prone, i.e., produces mutations.
D. all of the choices
37. The Ames test
A. can be used to measure the mutagenicity of chemicals.
B. is used to measure the repair of thymine dimers.
C. is used to measure levels of oxygen free radicals.
D. none of the choices
38. A mutation from the most prevalent form of a gene to a mutant form is called a __________
mutation.
A. forward
B. reverse
C. wild card
D. escalating
39. A mutagen that inserts between the stacked bases of a DNA double helix, distorting the DNA
to induce single-pair insertions or deletions is called a(n) __________ agent.
A. insertional
B. interspersing
C. intercalating
D. distortional
40. Spontaneous mutations are caused by
A. errors in DNA replication.
B. insertion of transposons.
C. radiation.
D. errors in DNA replication and insertion of transposons
E. all of the choices
41. Which of the following is the most error-prone of the repair mechanisms?
A. postreplication repair
B. recombination repair
C. SOS repair
D. photoreactivation
42. A __________ mutation does not alter the amino acid sequence of the resulting protein.
A. missense
B. nonsense
C. silent
D. none of the choices
43. As the result of exposure to a mutagen, cytosine is substituted for thymine in one strand of
DNA. Upon subsequent DNA replication, one of the daughter cells will have a GC pair in this
position instead of an AT pair. This is called a(n) __________ mutation.
A. transversion
B. transition
C. frameshift
D. insertion
44. Which of the following can lead to transition mutations?
A. incorporation of a base analog that exhibits different base-pairing properties from the base it
replaces
B. chemical modification of an existing base in the DNA so that in the next round of replication
it will pair differently from the unmodified base
C. incorporation of a base analog that exhibits different base-pairing properties from the base it
replaces and chemical modification of an existing base in the DNA so that in the next round of
replication it will pair differently from the unmodified base
D. a small insertion or deletion
45. Which of the following is considered a reverse mutation that will restore the wild type
phenotype?
A. true reversion back to the wild type base sequence
B. mutation to a different base sequence, but one that restores the amino acid sequence in the
protein to the wild type sequence
C. a mutation that restores the function of a protein even though it does not restore the base
sequence or the amino acid sequence to the wild type
D. all of the choices
46. Which of the following types of mutation may play an important role in driving evolution
because they are often nonlethal and, therefore, remain in the gene pool?
A. nonsense
B. missense
C. frameshift
D. deletion
47. Which one of the following contributes to the utility of the strains of Salmonella typhimurium
used in the Ames reversion assay?
A. They are highly permeable to test substances.
B. They are defective in DNA repair and, therefore, cannot readily repair damage done by the
test substances.
C. It is very straightforward to assay the conversion of their histidine auxotrophy mutations to
histidine prototrophy.
D. all of the choices
48. Repair of thymine dimers using light to split the dimers apart into separate monomers is
called
A. photodedimerication.
B. photoreactivation.
C. photoreparation.
D. none of the choices
49. Repair of an apurinic or apyrimidinic site in DNA by AP endonuclease must be completed by
the action of
A. UvrABC endonuclease.
B. RecA protein.
C. DNA polymerase I.
D. none of the choices.
50. A mutation that changes the amino acid sequence of the resulting protein by substitution is
called a __________ mutation.
A. missense
B. nonsense
C. silent
D. none of the choices
51. Microbial strains that can grow on minimal medium are called __________.
A. autotrophs
B. auxotrophs
C. prototrophs
D. minitrophs
52. _______ are strains that are unable to grow on a minimal medium that supports growth of the
wild type strain but are able to grow on the minimal medium if one or more nutritional
supplements are added.
A. Autotrophs
B. Auxotrophs
C. Prototrophs
D. Minitrophs
53. Mutations that result in the death of an organism when expressed are called __________
mutations.
A. dominant
B. recessive
C. lethal
D. conditional
54. Lethal mutations can be maintained in diploid organisms if they are
A. dominant.
B. recessive.
C. deletions.
D. none of the choices
55. Lethal mutations can be recovered in haploid organisms if they are
A. dominant.
B. active.
C. conditional.
D. none of the choices
56. A __________ mutation is one that causes premature termination of the synthesis of the
protein product.
A. missense
B. nonsense
C. silent
D. none of the choices
57. In an HFR  F+ mating, the conjugation bridge usually breaks before chromosomal transfer is
complete. Therefore, the recipient remains F-.
True False
58. In the mechanics of conjugation, exclusive of gene transfer, Hfr and F+ strains behave the
same.
True False
59. During specialized transduction mediated by phage lambda, helper phage function as sites of
integration and provide functions needed for replication of the transducing phage.
True False
60. Transposable elements have been found only in procaryotes and do not appear to play a
major role in eucaryotes.
True False
61. In an F+  F- mating, all or part of the host chromosome usually is transferred to the
recipient.
True False
62. The conjugation bridge in an Hfr  F- mating usually breaks before chromosome transfer is
complete; however, because at least part of the plasmid is transferred first, the recipient becomes
F+.
True False
63. When a genome is mapped with Hfr conjugation, a high frequency of gene transfer means
that the gene is located close to the integration site of the plasmid.
True False
64. Transformation has been observed in only a limited number of species in nature, but we have
found ways to force the process upon other species in the laboratory.
True False
65. Approximately half of known animal carcinogens can be detected by the Ames test.
True False
66. Photoreactivation repairs thymine dimers by splitting them back into separate thymines.
True False
67. The frequency of cotransfer of two genes can be used to construct __________ maps
indicating the distance of two genes from each other.
68. A __________ is a latent form of a virus genome that remains within the host without
destroying it.
69. A __________ is a piece of extrachromosomal DNA that has its own replication origin.
70. A plasmid that can either exist independently of the chromosome or be integrated into it is
called a(n) __________.
71. Plasmids that have genes for pili and can transfer copies of themselves to other bacteria
during conjugation are called __________ plasmids.
72. __________ __________ is the process by which some cells are capable of degrading an
exogenote.
73. In order to take up a naked DNA molecule, a cell must be __________, which may occur
only at certain stages in the life cycle of the organism.
74. In mismatch repair on newly replicated DNA, enzymes distinguish between old and newly
replicated DNA strands based on the fact that newly replicated DNA strands are ________
methylated relative to older DNA.
75. The __________ __________ is the most prevalent form of a gene in a population.
76. __________ are physical or chemical agents that cause mutation.
77. __________ mutations occur in the promoter or operator region of a gene or set of genes and
affects the expression of the downstream genes without affecting the amino acid sequences of the
gene products.
78. __________ mutations affect only a single base pair in a gene.
79. Mutations resulting from exposure to physical or chemical agents are called __________
mutations.
80. The term ____________ refers to the abnormally high rate of mutation that results from the
activation of specific mutator genes.