Ch.13 Bacterial Genome Replication And Expression Exam Prep

Prescott's Microbiology, 11e (Willey)

Chapter 13 Bacterial Genome Replication and Expression

1) Proteins that recognize unfolded polypeptides and help them fold into their proper conformations are called ________.

2) Signal recognition particles (SRPs) are associated with the Sec translocation system.

3) When a protein is synthesized, cis- or trans-splicing of that protein occurs ________.

A) following translation

B) between transcription and translation

C) during transcription

D) prior to transcription

4) What might be a reason for the accumulation of improperly folded protein complexes in the bacterial cell cytoplasm following translation?

A) A problem exists with the functioning of molecular chaperones

B) The cell is synthesizing proteins too rapidly

C) Polysomes are forming on the mRNA

D) The proteins are being transcribed but not translated

5) The Tat and Sec pathways are protein translocation systems.

6) The Sec system is used by ________.

A) both Gram-positive and Gram-negative bacteria

B) neither Gram-positive nor Gram-negative bacteria

C) Gram-positive bacteria only

D) Gram-negative bacteria only

7) During ________ proteins are moved from the cytoplasm to the membrane or periplasmic space, while during ________ proteins are moved from the cytoplasm to the external environment.

A) translocation; secretion

B) secretion; translocation

C) transcription; translation

D) translocation; translation

E) secretion; translation

8) A bacterial cell that secretes proteins by types II and V systems is most likely Gram-negative.

9) Prior to secretion, Gram-negative bacterial proteins are translocated across one membrane while Gram-positive proteins are translocated across two membranes.

10) Select the secretion systems that are found in both Gram-positive and in Gram-negative bacteria.

A) Type 1

B) Type II

C) Type III

D) Type IV

11) 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

12) During translation elongation, which event happens last?

A) A tRNA carrying an amino acid binds to the A site.

B) A peptide bond forms.

C) A tRNA molecule translocates from the A site to the P site.

D) A tRNA molecule translocates from the P site to the E site.

13) Which is true regarding translation in bacteria?

A) Translation begins with formation of the 30S initiation complex.

B) Translation ends when the Shine-Dalgarno sequence is reached.

C) The 70S ribosome is composed of a 20S and 50S subunit.

D) All of the choices are correct.

14) DNA polymerase and aminoacyl-tRNA synthase are similar in that both have proofreading ability, but differ in the substrates that they act upon.

15) This initiator tRNA of the bacterium Escherichia is a modified form of the initiator tRNA used by the yeast Saccharomyces.

16) If you wished to design an antimicrobial agent that prevented the formation of the 70S initiation complex in bacterial translation, which molecule should specifically be targeted?

A) IF-3

B) mRNA

C) Peptidyl transferase

D) EF-1

17) Aminoacyl-tRNA synthetases catalyze covalent addition of ________ ________ to tRNAs.

18) 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

19) In ________, ribosomes can attach to the mRNA and begin translation even though transcription has not been completed.

A) bacteria

B) eukaryotes

C) fungi

D) protozoa and some plants

20) A complex consisting of a single mRNA molecule with several ribosomes is called a ________.

A) polysome

B) multisome

C) maxisome

D) proteosome

21) The ________ reaction sequentially links adjacent amino acids into the growing polypeptide chain.

A) dipeptidation

B) transpeptidation

C) peptidation

D) propeptidation

22) 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

23) In order to add a single amino acid to a growing polypeptide chain, a total of ________ molecules or ATP of GTP are utilized.

A) two

B) three

C) four

D) six

24) The first amino acid in a bacterial protein is N-formylmethionine; the presence of the formyl group makes it the initiator amino acid.

25) 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

26) ________ 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)

27) How many different termination codons are used in translation?

A) One

B) Two

C) Three

D) Four

28) How many RNA codons encode 60 amino acids?

A) 60

B) 180

C) 20

D) 30

29) Which set of codons terminate transcription in most organisms?

A) UGA, UAG, UAA

B) AGU, UAG, UAA

C) ACT, TAC, ATT

D) TGA, TAG, TAA

30) What would be the most likely outcome if the genetic code was not degenerate? 

A) The effect of some mutations would increase.

B) The effect of some mutations would decrease.

C) The mutation rate would remain the same.

D) The number of stop codons would increase.

31) Two amino acids that are found in some proteins due to exceptions in the universal genetic code are ________.

A) pyrrolysine and selenocysteine

B) lysine and selenocysteine

C) pyrrolysine and cysteine

D) lysine and cysteine

32) Which of the following are exceptions to the universal genetic code that is used by most organisms? 

A) Selenocysteine

B) Stop

C) Pyrrolysine

D) Lysine

E) Phenylalanine

33) 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

34) Which of the following is the initiator codon?

A) AUG

B) UAA

C) UAG

D) UGA

35) Which of the following is not a termination codon?

A) AUG

B) UAA

C) UAG

D) UGA

36) 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

37) The genetic code is translated in groups of ________ bases.

A) two

B) three

C) four

D) five

38) The stop codons are translated codons; that is, they specify amino acids to be inserted into the last position of a growing polypeptide chain.

39) Messenger RNA molecules that direct the synthesis of more than one polypeptide are said to be ________.

40) Choose the description below that best matches the current model of RNA polymerase holoenzyme.

A) A core enzyme composed of five polypeptides bound by a transcription factor.

B) A core enzyme composed of five polypeptides bound by ribosomes.

C) A core enzyme composed of five sigma factors bound by a polypeptide chain.

D) An open complex or "bubble" formed by DNA, mRNA, and RNA polymerase.

41) During transcription elongation, how many pyrophosphate molecules are produced from the incorporation of 20 ribonucleoside monophosphates?

A) 20

B) 40

C) 60

D) 5

42) In Escherichia coli, if σ70 is not bound to RNA polymerase core enzyme, active transcription of the gene is not occurring.

43) Which of the following is a correct comparison between RNA polymerase holoenzyme that functions in transcription and the primase enzyme that functions in DNA replication?

A) Both enzymes synthesize RNA.

B) Both enzymes are bound by sigma factor.

C) Both enzymes synthesize DNA.

D) Both enzymes are composed of RNA.

44) Order the following regions of a gene from the most upstream region (1) to the most downstream region (5).

1. -35 consensus sequence

2. Pribnow box

3. coding sequence

4. rut site

5. terminator

45) 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

46) Which modification of the terminator region of a gene would specifically prevent rho-independent termination?

A) Change in the adenine-rich sequence of nucleotides of the terminator region.

B) Change in the adenine-thymine sequence of the Pribnow box.

C) Change in the sequence that encodes the mRNA leader.

D) Change in the rut binding site.

47) Which of the following is common to both factor-dependent and factor-independent transcription termination?

A) Both types of termination occur following a pause by the polymerase.

B) Both types of termination are associated with rho termination factor.

C) Both types of termination involve NusA protein.

D) None of the choices are correct.

48) 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

49) 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

50) 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 eukaryotic mRNAs

51) 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

52) Which statement defends the concept that the term "gene" is better defined as a nucleotide sequence that encodes for one or more functional products rather than encoding for one or more functional proteins?

A) Products of genes include ribonucleotides as well as proteins.

B) Intron sequences in DNA do not encode proteins.

C) The genetic code is redundant, therefore the same codon may be encoded by different DNA triplets.

D) Genes in bacteria are organized as operons that can lead to several protein products.

53) If the DNA of a new discovered organism exhibits genes that are arranged as operons and lacks intron sequences, the hypothesis that this organism is bacterial rather than mammalian would be supported by the evidence.

54) If the product of a functional gene is not a protein, what other product(s) might be encoded by the gene?

A) tRNA and rRNA

B) tRNA and mRNA

C) mRNA and rRNA

D) mRNA, tRNA, and RNA

55) Modify the following statement to make it correct:  Ribozymes are ribonucleosomes used by bacteria and eukaryotic cells to modify DNA.

A) Ribozymes are ribonucleases used by bacteria and eukaryotic cells to modify RNA.

B) Ribozymes are ribonucleosomes used by bacteria and eukaryotic cells to modify RNA.

C) Ribozymes are ribonucleases used by bacteria and eukaryotic cells to modify DNA.

D) Ribozymes are ribonucleosomes used only by eukaryotic cells only to modify RNA.

56) The transcribed and translated region of a gene is the ________ region.

A) leader

B) promoter

C) coding

D) trailer

57) Which of the following is in the coding region of a gene?

A) Promoter

B) Leader

C) Trailer

D) None of the choices are correct.

58) The unexpressed regions of split genes are called ________.

A) exons

B) endons

C) introns

D) codons

59) On mRNA molecules, a nontranslated sequence called the ________ usually precedes the initiation codon.

60) Messenger RNA molecules have a nontranslated sequence called the ________, which is located downstream of the termination codon.

61) The region at which the RNA polymerase binds is the ________ region.

A) leader

B) promoter

C) coding

D) trailer

62) The transcribed, but not translated, sequence that is immediately upstream of the region that encodes the functional product is called the ________ region.

A) leader

B) promoter

C) coding

D) trailer

63) A consensus sequence in the untranslated leader sequence of a prokaryotic mRNA, which serves as a ribosome binding site is called the ________ - ________ sequence.

64) The coding sequence in the DNA of ________ is normally continuous; that is, it is not interrupted by noncoding sequences.

A) bacteria

B) plants

C) mammals

D) most insects

65) 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

66) The noncoding sequences located between the start codon and the stop codon in interrupted genes are called introns.

67) The genetic information in DNA is divided into units called ________.

A) proteins

B) genes

C) genotype

D) phenotype

68) Bacterial chromosomes, unlike eukaryotic chromosomes, often consist of a single replicon.

69) A scientist wishes to develop an antimicrobial agent that specifically targets replication elongation in Escherichia coli without interfering with proteins that catalyze other replication processes. Which of the following experimental designs is most appropriate for the scientist to explore?

A) Develop a molecule that interferes with the DNA-binding ability of DNA polymerase III core enzyme

B) Modify an existing antibiotic to act as a competitive inhibitor of DNA polymerase I

C) Design a drug that modifies the structural configuration of DNA at the oriC locus

D) Create a novel protein that acts as a competitive inhibitor of the DNA ligase binding site

70) While examining the sequence of nucleotides in the replicon region of bacterial DNA, you note an abundance of adenine and thymine base pairs. This leads you to conclude that this particular section of the DNA must be the ________.

A) oriC site

B) Pribnow box

C) Shine-Dalgarno sequence

D) ter site

71) 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

72) Choose the correct order of proteins that function in the initiation, elongation, and termination stages of DNA replication.   

A) DnaA, DNA polymerase III, DNA polymerase I, DNA ligase

B) DnaA, DNA polymerase I, DNA polymerase III, DNA ligase

C) DNA polymerase III, DNA polymerase I, DNA ligase, DnaA

D) DNA polymerase I, DnaA, DNA polymerase III, DNA ligase

73) During DNA replication, deoxyribonucleosides are added to the 5' end of Okazaki fragments and to the 3' end of the leading strand. 

74) In terms of relatedness to a specific cellular process, which protein does not belong with the others?

A) RNA polymerase holoenzyme

B) DNA polymerase holoenzyme

C) Ribonuclease

D) DNA ligase

75) Catenanes are interlocked chromosomes that form during the termination stage of DNA replication.

76) Bacteria with DNA described as having "hairpin ends with inverted repeats" must not have circular chromosomes. 

77) Which of the following is a region of DNA at the end of a linear chromosome?

A) Telomere

B) Primer

C) Intron

D) Exon

78) Which enzyme is a topoisomerase?

A) DNA gyrase

B) DNA ligase

C) DNA polymerase I

D) DNA polymerase III

79) Each chromosome has one or more ________ site(s) where replication begins.

A) promoter

B) replicon

C) origin

D) bifurcate

80) 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

81) DNA replication is a complex process, and, as a result, the frequency of error is quite high.

82) During replication, which enzyme unwinds the two strands of the DNA molecule from one another?

A) Ligases

B) Unwindases

C) Helicases

D) Primases

83) Over twisting or under twisting of helical DNA generates ________.

A) hypertwists

B) hypotwists

C) hypercoils

D) supercoils

84) Bacterial 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

85) If you were to design a novel hydrophobic protein, which type of monomers would be most essential to incorporate in the molecule in order to achieve the desired result?

A) Amino acids with nonpolar side chains

B) Amino acids with charged side chains 

C) Purine-containing deoxyribonucleotides

D) Hydrophobic nucleic acids

E) Polar amino acids

86) How many phosphodiester bonds are needed to join 50 deoxyribonucleotides in a DNA strand?

A) 49

B) 50

C) 51

D) 100

E) 102

87) A molecule of RNA has 99 phosphodiester bonds connecting ________ ribonucleotides.

88) The number of N and C termini in a polypeptide chain is equal to the number of amino acids that make up that chain.

89) The molecular weights of a nucleic acid and an amino acid are approximately the same. 

90) Which of the following is not present in DNA?

A) Alpha carbon

B) 5'-carbon

C) Minor groove

D) 3'-hydroxyl

E) Double helix

91) 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.

92) The B form of the 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.

93) Which of the following nitrogenous bases is usually found in RNA but not in DNA?

A) Adenine

B) Thymine

C) Uracil

D) Guanine

94) If 20% of nucleotides in the DNA of a particular organism contain thymine, estimate the percentage of cytosine that is present in the DNA.  

A) 30%

B) 20%

C) 15%

D) 80%

E) 40%

95) Which of the following is NOT a pyrimidine?

A) Adenine

B) Cytosine

C) Thymine

D) Uracil

96) Which of the following is not a complementary base pair found in DNA molecules?

A) Adenine-thymine

B) Guanine-cytosine

C) Adenine-uracil

D) All of the choices are correct.

97) 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) Nucleotides are joined by phosphodiester bonds.

C) Adjacent nucleotides are stacked on top of each other, one base pair every 0.34 nm.

D) All of the choices are correct.

98) The two strands of a DNA molecule are ________; that is, they are oriented in opposite directions.

99) How were experiments done by Griffith similar to those done by Avery, MacLeod, and McCarty?

A) Both used pneumococcal bacteria

B) Both used purified DNA

C) Both used a mouse host

D) Both were done in the 1940s

E) Both used enzymes that destroyed DNA

100) Which was common to experiments done by Avery and colleagues as well as Hershey and Chase?

A) Radioactive DNA

B) Virulent bacteriophage

C) Bacterial cells

D) Radioactive protein

E) Escherichia coli

101) In the Hershey and Chase experiment, how did labeling DNA and protein with different radioactive isotopes demonstrate that DNA, rather than protein, carried the genetic information in the T2 virus? 

A) Researchers could track which part of the virus entered a bacterial cell.

B) Researchers could use radio labeling to inactivate DNA and protein in the bacteria. 

C) Researchers could distinguish bacterial DNA from viral protein.

D) Researchers could better elucidate DNA or protein structure.

E) Researchers could monitor how DNA interacted with protein in the virus. 

102) By using enzymes that destroyed DNA, RNA, or protein, Avery and colleagues were able to determine which of the three molecules was required to transform bacterial cells.  

103) How could the Hershey and Chase experimental procedure be redesigned to support a hypothesis that RNA carries genetic information? 

A) Replace T2 bacteriophage with an RNA virus

B) Replace Escherichia with an RNA virus

C) Use 35S to label an RNA virus and 32P to label a DNA virus

D) Extract RNA from Escherichia and mix it with the T2 bacteriophage

E) Use 35S and 32P to label the same components of an RNA virus and T2 bacteriophage, then add both viruses to Escherichia cells

104) Hershey and Chase used 35S-labeled protein and 32P-labeled DNA of T2 bacteriophage to infect cells of Streptococcus pneumoniae bacteria. 

105) Hershey and Chase demonstrated that when the bacteriophage T2 infected its host cell, the ________ is injected into the host but the ________ remained outside.

106) Griffith's experiment demonstrated transformation because a mouse injected with live R and heat-killed S strains of Streptococcus pneumoniae resulted in death of the mouse and the isolation of live R as well as live S cells. Hypothesize as to the type of cells that Griffith would have observed if transformation had NOT occurred.

A) Griffith would have isolated only live R cells from the mouse host.

B) Griffith would have isolated both live R and heat-killed S cells from the mouse host.

C) Griffith would have isolated only live S cells from the mouse host.

D) Griffith would have isolated no cells from the mouse host.

107) Who first demonstrated transformation using mice and two strains of Streptococcus pneumoniae?

A) Griffith

B) Hershey and Chase

C) Avery, McCarty, and MacLeod

D) Watson and Crick

E) Jacob and Monod

108) You and a classmate are discussing early experiments in genetics, and you state that Avery, MacLeod, and McCarty provided the first evidence that DNA carries genetic information. Your classmate argues that Griffith was the first to demonstrate this. Which statement best defends your argument?

A) Although Griffith first demonstrated transformation, Avery, MacLeod, and McCarty provided evidence that DNA rather than protein or RNA was the transforming agent.

B) Avery, MacLeod, and McCarty worked with purified DNA extracts while Griffith worked with bacterial strains. 

C) Enzymes were used in the experiments carried out by Avery, MacLeod, and McCarty while Griffith transformed cells chemically or by using heat.

D) Because Avery, MacLeod, and McCarty did their experiments after those done by Griffith, they had much more information regarding the structure and function of DNA.

E) DNA used by Avery, MacLeod and McCarty was extracted solely from transformed strains of pneumococci, while Griffith used native pneumococcal strains.

109) Why did scientists originally believe that proteins, rather than DNA, were the molecules that directed protein synthesis?   

A) Proteins were the more complex molecules in which genetic information could be stored. 

B) Proteins were more likely to have catalytic properties for synthesis reactions.

C) Proteins were the same types of molecules as those that were being synthesized.

D) At the time, more was known about the structure of proteins than that of DNA.

110) DNA polymerases require which of the following elements to replicate DNA?

A) A template, a primer, a source of energy

B) A source of energy, an RNA strand, a ribosome

C) A ribosome, a template, an RNA polymerase

D) A source of energy, a template, an RNA polymerase

111) The genes that code for tRNA often contain multiple tRNA sequences controlled by a single promoter, requiring posttranscriptional modification by ribonucleases.

112) Bacterial ribosomes ________.

A) comprise two rRNA subunits, multiple proteins, and three tRNA binding sites

B) comprise two tRNA binding sites, three rRNA subunits, and multiple proteins

C) comprise two proteins, three tRNA binding sites, and multiple rRNA subunits

D) comprise multiple tRNA binding sites, three proteins, and two rRNA subunits

113) One benefit of transporting molecules via outer membrane vesicles and extracellular vesicles versus a typical secretion system is that ________.

A) the vesicle contents are protected by the lipid bilayer that surrounds them, extending their viability outside of the cell

B) transport from one cell to another occurs at a much more rapid rate

C) it requires much less energy to transport the molecules in vesicles

D) vesicles form regardless of the environmental conditions that surround the bacterial cells

114) In bacteria, splicing of proteins occurs ________.

A) cotranslationally, and minimally involves splicing the N-formyl group from the initiator amino acid as it exits the ribosome

B) posttranslationally, and minimally involves splicing the N-formyl group from the initiator amino acid as it exits the ribosome

C) posttranslationally, and always involves splicing the first two amino acids from the N-terminus as it exits the ribosome

D) cotranslationally, and always involves splicing the first two amino acids from the N-terminus as it exits the ribosome

115) Membrane vesicles are used to transport material between cells as an alternative to protein secretion systems. Regardless of the nature of the bacterial envelope, all vesicles are produced by the same mechanism.