BIO 360 EXAM 5 CH 10, 11, 12
1. The flow of genetic information is RNA → DNA in a) all organisms b) all prokaryotes c) retroviruses d) no known organisms
C. Retrovirus
68. The match between codon and anticodon is one of the many proofreading aspects of protein synthesis. a) True b) False
TRUE
3. The famous Meselson and Stahl experiment showed: a) DNA is replicated by a semi-conservative mechanism. b) The direction of DNA synthesis proceeds 5' → 3'. c) The isotope 15N is denser than 14N. d) DNA replication is semi-conservative and 15N is denser than 14N. e) All of these are correct.
a) DNA is replicated by a semi-conservative mechanism.
52. The timing of expression of an operon in E. coli is influenced by all of the following, except: a) Repressors b) Co-repressors c) Presence of substrates of the operon which need to be degraded d) Inducers e) All of these influence the timing of expression
a) Repressors
19. The proofreading of DNA is especially good because "the identity of each base pair is checked before the enzyme moves on to the next base pair." a) True b) False
a) True
72. A polysome is a) a complex consisting of one mRNA to which several ribosomes are attached b) a polypeptide chain in the process of being formed c) an intermediate stage in the self-assembly of ribosomes d) an aggregate of ribosomal proteins
a) a complex consisting of one mRNA to which several ribosomes are attached
65. An aminoacyl-tRNA is initially bound to the ribosome a) at the A site on the 50S subunit b) at the P site on the 50S subunit c) at the A site on the 30S subunit d) at the P site on the 30S subunit
a) at the A site on the 50S subunit
48. The promoter region of DNA a) contains sequences that direct the binding of RNA polymerase b) tends to be G-C rich c) starts at the start of transcription and contains the coding region for the first 15 nucleotides incorporated into RNA d) binds specifically to the core RNA polymerase
a) contains sequences that direct the binding of RNA polymerase
71. The formylation of methionine in prokaryotes a) depends on two different tRNAs, where methionine can be formylated when bound to one form and not the other b) depends on two different tRNAs, where methionine can be formylated when bound to either one c) depends on one tRNA, where methionine is formylated after binding d) takes place before methionine is bound to tRNA
a) depends on two different tRNAs, where methionine can be formylated when bound to one form and not the other
5. The direction of synthesis of DNA is a) from the 5' end to the 3' end on both strands b) from the 3' end to the 5' end on both strands c) from the 5' end to the 3' end on one strand and from the 3' end to the 5' end on the other strand d) none of the above
a) from the 5' end to the 3' end on both strands
62. RNA polymerases from prokaryotes and eukaryotes a) have sequence homology in catalytic subunits b) have identical σ factors c) differ because there is no analogue to the prokaryotic α subunit in eukaryotes d) have the same number and kind of subunits
a) have sequence homology in catalytic subunits
39. The enzyme principally responsible for RNA synthesis in Escherichia coli a) is a multisubunit enzyme b) consists of a single polypeptide chain c) requires Mn2+ for activity d) requires a DNA primer
a) is a multisubunit enzyme
2. What is the requirement for a template strand in DNA replication? a) it serves as a guide in determining the next nucleotide to be added according to the Watson-Crick base pairing scheme b) it serves as the start point for the new DNA strand c) it allows the DNA polymerase to move along it easily d) it is a substrate for the 3'-5' exonuclease activity
a) it serves as a guide in determining the next nucleotide to be added according to the Watson-Crick base pairing scheme
24. One of the most important ways in which DNA is modified after synthesis is a) methylation of bases b) covalent binding of proteins to the sugar moieties c) splicing of RNA "leaders" d) electrostatic binding of negatively charged counterions
a) methylation of bases
55. Cyclic AMP affects transcription by a) triggering the action of several protein factors b) phosphorylating a subunit of RNA polymerase c) phosphorylating a transcription factor d) inhibiting DNA looping
a) triggering the action of several protein factors
1. Which of the following strategies is used in DNA repair? a) nick translation b) mismatch repair c) base excision repair d) all of the above
all of the above
4. All the following describe the general mechanism of DNA synthesis, except: a) One strand is made 5' → 3' while the other strand is made 3' → 5'. b) The strands become separated during synthesis. c) Synthesis occurs in both directions from the starting site of synthesis. d) Synthesis of DNA is a very accurate process. e) All of these are correct.
all of the above
69. Which of the following is necessary for chain termination in protein synthesis? a) termination codons of mRNA b) release factors c) GTP d) all of the above
all of the above
41. Operator regions at the end of prokaryotic genes contain all the following, except: a) The binding site for repressors. b) The binding site for RNA Pol. c) The binding site for factors which enhance RNA polymerization. d) The binding site for sigma factor. e) All of these.
all of these
42. Which of the following offers the best description of a Pribnow box? a) A promoter consensus sequence located at approximately -35. b) A promoter consensus sequence located at approximately -10. c) A sequence forming a hairpin loop signaling the termination of transcription. d) A sequence immediately surrounding the start site of transcription.
b) A promoter consensus sequence located at approximately -10.
10. The primer for in vivo DNA replication is: a) The 3' hydroxyl of the preceding Okazaki fragment. b) A short piece of RNA. c) A nick made in the DNA template. d) A primer is not always required for DNA replication. e) All of these are true.
b) A short piece of RNA.
32. Transcription of RNA and replication of DNA are similar in all these ways, except: a) Nucleoside triphosphates are the precursors. b) Both strands of DNA are copied. c) Base pairing is used to copy the sequence in a precise manner. d) The chain grows for the 5' to the 3' end. e) All of these are similarities between RNA and DNA synthesis.
b) Both strands of DNA are copied.
37. These terms can be used interchangeably to denote the complementary strand in DNA, except: a) Template strand b) Coding strand c) Antisense strand d) Negative or "-" strand e) All these terms describe the complementary DNA strand
b) Coding strand
16. Optimal DNA replication requires the coordinated effort of all of the following, except: a) Primase b) DNA Polymerase II. c) Single strand binding proteins. d) Gyrase e) All of these are necessary.
b) DNA Polymerase II.
40. Which of the following correctly describes a difference between RNA & DNA polymerases? a) RNA polymerases usually do not need a template, while DNA polymerases do. b) DNA polymerases usually require a primer (i.e., they can only continue a strand, not start one), while most RNA polymerases do not. c) RNA polymerases usually synthesize introns, while DNA polymerases synthesize cistrons. d) RNA polymerases polymerize 5' —> 3', while DNA polymerases polymerize 3' —> 5'.
b) DNA polymerases usually require a primer (i.e., they can only continue a strand, not start one), while most RNA polymerases do not.
58. The following are all true about eukaryotic and prokaryotic RNA polymerases, except: a) There are 3 different RNA polymerases in eukaryotes, instead of just one. b) Eukaryotic polymerases have the same number of subunits as prokaryotic ones. c) Only prokaryotic polymerases use sigma factor. d) The enzymatic mechanism is the same for both types of organisms. e) All of these are true.
b) Eukaryotic polymerases have the same number of subunits as prokaryotic ones.
8. The many subunits of DNA Polymerase III are needed to do all the following, except: a) Polymerization. b) Ligating the final products. c) Proofreading. d) Clamping on to the template. e) All of these.
b) Ligating the final products.
33. All the following statements describe the general mechanism of RNA synthesis, except: a) The DNA strands become separated during synthesis b) Synthesis of RNA is a very accurate process c) The template strand is read in the 3' → 5' direction d) All 4 ribonucleotides are required e) All of these describe RNA synthesis
b) Synthesis of RNA is a very accurate process
70. Protein synthesis in prokaryotes always starts with a) a methionine residue b) a formylmethionine residue c) a cysteine residue d) no specific residue
b) a formylmethionine residue
51. Operons a) control the expression of constitutive genes b) are subject to positive or to negative control c) are not affected by mutations in the genes for repressors or inducers d) occur in both prokaryotes and eukaryotes
b) are subject to positive or to negative control
45. Initiation of RNA biosynthesis involves a) recognition of the promoter region by the α subunit of RNA polymerase b) conversion of the closed-promoter complex to the open-promoter complex c) binding of one of the α subunits of RNA polymerase to each strand of DNA d) incorporation of four pyrimidine nucleotides in succession
b) conversion of the closed-promoter complex to the open-promoter complex
28. One of the most important ways in which eukaryotic DNA differs from that of prokaryotes is a) prokaryotic DNA is complexed to proteins whereas eukaryotic DNA is not b) eukaryotic DNA is complexed to proteins whereas prokaryotic DNA is not c) DNA synthesis in eukaryotes takes place in the opposite direction from that in prokaryotes d) there is no requirement for a primer in the synthesis of eukaryotic DNA
b) eukaryotic DNA is complexed to proteins whereas prokaryotic DNA is not
29. Replication of eukaryotic DNA a) must occur faster than replication of prokaryotic DNA b) must be controlled to coordinate with the cell cycle c) takes place during mitosis d) takes place twice during each cell cycle
b) must be controlled to coordinate with the cell cycle
76. A Shine-Dalgarno Sequence is a a) sequence of nucleotides in the DNA that interacts with the σ-subunit of RNA polymerase to begin transcription. b) sequence of nucleotides in an mRNA that interacts with the small subunit of a ribosome to begin translation. c) sequence of nucleotides in the DNA that interacts with ρ-protein to terminate transcription. d) sequence of nucleotides in an mRNA that functions to terminate translation.
b) sequence of nucleotides in an mRNA that interacts with the small subunit of a ribosome to begin translation.
14. What is the need for a primer strand in DNA replication? a) it ensures the fidelity of the newly synthesized DNA strand b) the DNA polymerases require a preexisting strand with a nucleotide having a 3'-OH c) the DNA polymerases require a preexisting strand with a nucleotide having a 5'-OH d) it ensures the integrity of the new DNA
b) the DNA polymerases require a preexisting strand with a nucleotide having a 3'-OH
63. A frequently encountered aspect of binding of RNA polymerase II to its promoter is a) the lack of upstream elements b) the presence of the TATA box c) the highly conserved sequence at the start of transcription d) the requirement for downstream elements
b) the presence of the TATA box
46. What is the need for a primer strand in transcription? a) it ensures the fidelity of the newly synthesized RNA strand b) there is none c) RNA polymerases requires a preexisting strand with a nucleotide having a 3'-OH d) RNA polymerase requires a preexisting strand with a nucleotide having a 5'-OH
b) there is none
7. When the synthesis of new DNA is directed by an original template DNA molecule a) the DNA produced has two newly formed strands (no change in the original DNA) b) two DNA molecules are formed, each with one new strand and one strand from the original DNA c) there is random arrangement of newly formed and original DNA on the two strands of the DNA produced d) no information is available on this subject
b) two DNA molecules are formed, each with one new strand and one strand from the original DNA
15. Nicked segments of single-stranded DNA are linked by a) DNA polymerase b) DNA-binding protein c) DNA ligase d) DNA gyrase
c) DNA ligase
59. Which enzyme transcribes genes encoding tRNA in eukaryotes? a) RNA polymerase I b) RNA polymerase II c) RNA polymerase III d) Different tRNAs are transcribed by different RNA polymerases.
c) RNA polymerase III
18. Repair of DNA is usually carried out by a) hydrolysis of the entire damaged DNA molecule and synthesis of new DNA b) hydrolysis of one strand of the damaged DNA molecule and synthesis of a new strand c) a cut-and patch process d) introducing additional supercoiling in the molecule
c) a cut-and patch process
64. A transcription factor is a) a subunit of RNA polymerase II that does not have a prokaryotic analogue b) the part of the promoter sequence closest to the start of transcription c) a protein other than RNA polymerase that is involved in transcription d) a sequence that determines whether an upstream element will be an enhancer or silencer
c) a protein other than RNA polymerase that is involved in transcription
27. In eukaryotic, but not prokaryotic, DNA replication a) topoisomerases are required b) a primer is needed on the lagging strand only c) histone biosynthesis must take place d) there is only one origin of replication
c) histone biosynthesis must take place
61. Transcription in eukaryotes differs from RNA synthesis in prokaryotes a) by requiring a primer b) by simplifying the process with multifunctional enzymes c) in using more complex σ factors d) by having three RNA polymerases rather than one
c) in using more complex σ factors
56. Control of transcription in prokaryotes does not involve a) enhancers b) silencers c) leucine zipper proteins d) alternative σ factors
c) leucine zipper proteins
54. A mutation in the lac A gene would result in a) continuous production of the proteins encoded by the three structural genes b) continuous production of the lac repressor c) normal operation of the lac operon, but with an alteration in the proteins encoded by the lac A gene d) no transcription from the lac operon
c) normal operation of the lac operon, but with an alteration in the proteins encoded by the lac A gene
22. Ultra-violet light principally causes which of the following damages to DNA? a) mismatches between stands b) breaks in the phosphodiester backbone of the DNA strand c) thymine dimerization d) methylation of specific bases
c) thymine dimerization
43. RNA polymerase a) can bind at any location on DNA to start RNA synthesis b) incorporates nucleotides into growing RNA from the 3' to the 5' end c) uses a template strand of to specify the sequence of bases in RNA d) has 3' → 5' exonuclease activity
c) uses a template strand of to specify the sequence of bases in RNA
47. Which is not associated with bacterial promoters? a) the transcription start site b) the Pribnow box c) the -35 element d) 3 antiterminator
d) 3 antiterminator
38. Chain termination occurs, in vivo, when: a) RNA Pol gets to the end of the DNA. b) The factor called rho (ρ) binds to the DNA. c) A hairpin loop forms in the template. d) Either a hairpin loop forms or rho is involved. e) All of these.
d) Either a hairpin loop forms or rho is involved.
36. The sigma (σ) subunit has all the following properties, except: a) It tells the RNA Poly where to sit down. b) It helps point the RNA Pol in the proper direction. c) It causes the RNA Pol to bind tightly to the DNA. d) It stays with the RNA Pol throughout synthesis. e) All of these describe the sigma factor.
d) It stays with the RNA Pol throughout synthesis.
34. The universal features of RNA transcription include all the following, except: a) Release of PPi from a nucleoside triphosphate b) Synthesis from the 5' end to the 3' end c) Base pairing of A to U and G to C d) Use of a primer e) All of these describe RNA synthesis.
d) Use of a primer
6. An important process in the synthesis of new DNA is a) proofreading and repair b) unwinding of the double helix c) protection of single-stranded regions from nuclease action d) all of the above
d) all of the above
49. In prokaryotic RNA synthesis a) the rate of incorporation of nucleotides is constant throughout the elongation process b) the ρ (rho) protein is always required for termination c) a unique series of three bases leads to termination d) inverted-repeat sequences in the DNA being transcribed can lead to termination
d) inverted-repeat sequences in the DNA being transcribed can lead to termination
66. In protein synthesis formation of new peptide bonds is catalyzed by a) elongation factor EF-Tu b) elongation factor EF-Ts c) elongation factor EF-G d) peptidyl transferase
d) peptidyl transferase
57. Which of the following is not a characteristic of catabolite activator protein (CAP)? a) it is a positive regulator of the lac operon b) when the cell has sufficient glucose and lactose, CAP will not be bound to the CAP binding site c) CAP binding near the promoter site depends on CAP complexation with cAMP d) the binding of CAP to DNA requires ATP hydrolysis
d) the binding of CAP to DNA requires ATP hydrolysis
44. The promoter site is a) the start site for transcription in DNA b) the binding site for regulatory proteins that stimulate transcription c) the general region of DNA downstream from the start site d) the site on DNA at which RNA polymerase binds to initiate transcription
d) the site on DNA at which RNA polymerase binds to initiate transcription
67. After peptide bond formation takes place, what step is necessary for continuation of protein synthesis? a) binding of uncharged tRNA to the ribosome b) binding of EF-Tu c) binding of EF-Ts d) translocation of the ribosome
d) translocation of the ribosome
26. Thymine dimers are most often caused by a) improper function of DNA polymerase proofreading. b) ionizing radiation. c) free radicals. d) ultraviolet radiation.
d) ultraviolet radiation.
31. Differences between DNA polymerases in eukaryotes and bacteria include all, except: a) Some eukaryotic polymerases include a primase. b) All the eukaryotic enzymes are polymeric. c) Eukaryotes require a special enzyme to remove the RNA primer. d) Some eukaryotic polymerases include a primase and all are polymeric. e) All of these are correct.
e) All of these are correct.
35. RNA transcription differs from DNA replication in all of these ways, except: a) Substrates b) Primer c) Proofreading d) Template use e) All of these are different between RNA and DNA synthesis.
e) All of these are different between RNA and DNA synthesis.
60. The following are all key steps in activation of mRNA synthesis in eukaryotes, except: a) Binding of TBP to the DNA. b) Binding of other transcription factors. c) Binding of RNA Pol I. d) Phosphorylation of the RNA Pol. e) All of these are necessary to initiate RNA synthesis in eukaryotes.
e) All of these are necessary to initiate RNA synthesis in eukaryotes.
9. The universal features of DNA replication include all the following, except: a) Release of PPi from a nucleoside triphosphate. b) Synthesis from the 5' end to the 3' end. c) Base pairing of A to T and G to C. d) Use of a primer. e) All of these describe DNA synthesis.
e) All of these describe DNA synthesis.
53. The amount of expression of an operon in E. coli is influenced by all of the following, except: a) Availability of the specific sigma factor for that operon. b) How well the Pribnow box conforms to the consensus sequence. c) Attenuation mechanisms. d) Presence of 3' 5' cyclic AMP. e) All of these.
e) All of these.
11. Strands always grow in the 3' → 5' direction. a) True b) False
false
12. In E. coli, the leading strand is synthesized discontinuously while the lagging strand is synthesized in one piece. a) True b) False
false
13. Okazaki fragments are short DNA pieces that explain how DNA is synthesized on both strands. a) True b) False
false
21. It is so important to keep the DNA molecule fully connected that some repair mechanisms will actually allow mismatches or deletions from the DNA. a) True b) False
false
23. Since DNA Polymerase II has endonuclease activity, it is able to proofread its product when it is used in DNA repair. a) True b) False
false
74. The formyl group is added to methionine prior to attaching it to the initial tRNA. a) True b) False
false
75. In bacteria, each mRNA will bind to only one ribosome at a time. a) True b) False
false
1. The enzyme that attaches the Okazaki fragments together is called a ligase. a) True b) False
true
20. DNA repair mechanisms usually require an endonuclease to "nick" the duplex, so the repair enzymes can have access to the end of a DNA strand. a) True b) False
true
30. Linear eukaryotic DNA molecules have many origins of synthesis, while circular bacterial DNA usually have only one. a) True b) False
true
50. The promoter region is one term use to describe where RNA Pol binds to DNA. a) True b) False
true
73. In bacteria, translation of the mRNA begins during the synthesis of the mRNA. a) True b) False
true
