Deck 7: Molecular Biology of Microbial Growth

Question 1

Bacteria from the genus Caulobacter are used to model cellular differentiation in eukaryotes. The abundance of CtrA, DnaA, and GcrA separately control activity of other genes necessary for differentiation in Caulobacter. Thus, these three proteins can be classified as

A) activating sensors.
B) heterologous regulators.
C) differentiating regulons.
D) transcriptional regulators.

Answer 1

D

Question 2

All of the following are targets of currently used antibiotics EXCEPT

A) DNA synthesis.
B) biofilm formation.
C) transcription.
D) translation.

Answer 2

B

Question 3

Which of the following activities is a result of cyclic di-guanosine monophosphate synthesis?

A) transition from planktonic to sessile growth during biofilm formation
B) reduction in activity of flagellar motor
C) biosynthesis of extracellular matrix during biofilm formation
D) All of these answer choices activities are a result of cyclic di-guanosine monophosphate synthesis.

Answer 3

D

Question 4

________ prohibits re-initiation of chromosome replication.

A) DnaA-ATP
B) SeqA
C) oriC
D) FtsZ

Question 5

Which of the following proteins is most active in divisome complexes?

A) FtsZ
B) crescentin
C) MinCD
D) MreB

Question 6

A bacterium that lacks the mreB gene will have a ________ shape.

A) bacillus
B) coccoid
C) short bacillus
D) vibrio

Question 7

The major symptoms of the genetic disorder cystic fibrosis are caused due to biofilm formation by

A) Serratia marcesans.
B) Pseudomonas aeruginosa.
C) Vibrio cholera.
D) Bacillus subtilis.

Question 8

There are four basic stages to biofilm formation. Which of the following is the correct order of these stages?

A) attachment, colonization, development, dispersal
B) colonization, attachment, development, dispersal
C) development, colonization, attachment, dispersal
D) attachment, development, colonization, dispersal

Question 9

Once replication of the chromosome has begun, DnaA is inactivated

A) as a result of being blocked from oriC binding.
B) by increased expression of FtsZ.
C) as a result of increased binding to ATP.
D) by increased binding of DnaA-ATP to oriC.

Question 10

Pseudomonas aeruginosa is a(n) ________ pathogen.

A) opportunistic
B) idiopathic
C) pessimistic
D) iatrogenic

Question 11

What are the primary regulator units that control endospore formation?

A) allosteric proteins
B) antisense RNAs
C) riboswitches
D) sigma factors

Question 12

A bacterium that either partially or fully catabolizes an acyl-homoserine lactone will likely disrupt

A) attenuation.
B) chemotaxis.
C) endospore formation.
D) quorum sensing.

Question 13

Fluorescence microscopy allows visualization of all of the following EXCEPT

A) cytoskeletal proteins.
B) nuclear proteins.
C) interactions between cytoplasmic proteins.
D) All of these answer choices can be visualized.

Question 14

All of the following are TRUE statements concerning binary fission of microbial cells EXCEPT

A) the chromosome of the cell is replicated.
B) elongation of the cell occurs and the chromosomes are pushed apart.
C) a septum is formed across the midline of the cell.
D) daughter cells produced can be of different sizes.

Question 15

When a Bacillus anthracis population suddenly must form spores to survive a harsh nutrient poor environment, how do the cells obtain energy?

A) Cells in a growth phase that have not used up all of their energy will be the only ones to make endospores, which is why relatively few endospores are often made from a large population.
B) Intracellular energy reserves are quickly made available to produce endospores.
C) Slow responding cells are cannibalized by others that already began spore formation.
D) Global regulation is initiated to minimize energy waste in biosynthetic pathways and catabolic pathways are increased to consume remaining usable substrates to fuel spore formation.

Question 16

The typical generation time of Escherichia coli is approximately ________ under optimal environmental conditions.

A) 10 minutes
B) 20 minutes
C) 30 minutes
D) 40 minutes

Question 17

Prior to DNA replication, both strands of the chromosome are methylated on the ________ residue of the sequence-GATC-.

A) A
B) G
C) C
D) T

Question 18

The typical time required for chromosome replication in Escherichia coli is

A) 10 minutes.
B) 20 minutes.
C) 30 minutes.
D) 40 minutes.

Question 19

The Par system is necessary for

A) formation of a replication fork in Escherichia coli.
B) distribution of genetic material in replicating Caulobacter.
C) septum formation.
D) elongation of bacillus prior to cell division.

Question 20

Hemimethylated DNA is found on

A) the newly synthesized strand of DNA immediately after replication.
B) the parental strand of DNA immediately after replication.
C) both strands of dsDNA immediately after replication.
D) neither strand of DNA immediately after replication.

Question 21

Heterocysts are specialized cells that undergo

A) oxidative phosphorylation.
B) photophosphorylation.
C) nitrogen fixation.
D) lysine decarboxylation.

Question 22

Biofilm formation in Vibrio cholera is triggered by ________ cell densities and repressed by ________ cell densities.

A) high; high
B) low; low
C) high; low
D) low; high

Question 23

FtsA is related to ________, an important cytoskeletal protein in eukaryotes.

A) actin
B) myosin
C) tubulin
D) collagen

Question 24

Quorum sensing generally follows the mechanism of which type of regulation?

A) feedback inhibition
B) negative transcriptional regulation
C) positive transcriptional regulation
D) a two-component regulation system

Question 25

Shortage of key nutrients such as ________ results in transcription and secretion of a toxic protein that leads to cannibalization of neighboring cells of the same species.

A) magnesium
B) phosphate
C) calcium
D) iron

Question 26

Differential gene expression occurs in each of the following bacterium EXCEPT

A) Bacillus.
B) Mycobacterium.
C) Anabaena.
D) Caulobacter.

Question 27

What is the function of heterocysts in cyanobacteria such as Anabaena?

A) nitrogen fixation
B) sexual reproduction
C) asexual reproduction
D) photosynthesis

Question 28

The major shape-determining factor in Bacteria is the protein

A) FtsZ.
B) crescentin.
C) MreB.
D) MinD.

Question 29

Which of the following traits is NOT characteristic of the Caulobacter life cycle?

A) Cell division only occurs in the swarmer stage.
B) Cell division only occurs in the stalked cell stage.
C) Chromosome replication only occurs in the swarmer stage.
D) Chromosome replication and cell division only occurs in the stalked cell stage.

Question 30

Penicillins work by

A) activating autolytic enzymes.
B) blocking the transpeptidation reaction that forms peptidoglycan cross-links.
C) stimulating autolysins to form holes in the plasma membrane.
D) All of these answer choices are true.

Question 31

Which of the following is NOT a function of DnaA in Caulobacter?

A) initiation of DNA replication
B) initiation of swarming
C) transcriptional regulation
D) All of these answer choices are functions of DnaA.

Question 32

FtsZ is related to ________, an important protein involved in cell division.

A) actin
B) myosin
C) tubulin
D) collagen

Question 33

The curved-rod shape typical of Caulobacter is due to the protein(s)

A) crescentin.
B) MreB.
C) crescentin and MreB.
D) neither crescentin nor MreB.

Question 34

In the process of binary fission in Bacteria, which action occurs first?

A) formation of the divisome
B) DNA replication
C) cell elongation
D) cytokinesis

Question 35

σᶠ functions as a(n) ________ during endospore formation.

A) transcription factor
B) anti-sigma factor
C) protease
D) RNase

Question 36

Endospore formation is stimulated when

A) bacterial growth ceases due to limitation of an essential nutrient.
B) the bacterium is undergoing binary fission.
C) bacteria are dividing exponentially.
D) nutrient levels rise.

Question 37

What is the function of bactoprenol?

A) It is a hydrophobic alcohol that transports peptidoglycan precursors across the cytoplasmic membrane.
B) It is responsible for forming the peptide cross-links between muramic acid residues in adjacent glycan chains.
C) It triggers the recruitment of FtsZ and the initiation of the divisome.
D) It supplies the energy necessary for transpeptidation to occur.

Question 38

Biofilm formation in Pseudomonas aeruginosa is triggered by ________ cell densities and repressed by ________ cell densities.

A) high; high
B) low; low
C) high; low
D) low; high

Question 39

Proteins MinC, MinD, and MinE interact to

A) help guide FtsZ to the cell midpoint.
B) initiate peptidoglycan synthesis.
C) assist chromosome segregation.
D) determine cell shape.

Question 40

When Spo0A is highly phosphorylated

A) heterocyst formation is initiated.
B) stalk formation is initiated.
C) endospore formation is initiated.
D) photosynthesis is initiated.

Question 41

Biofilm formation is more likely to occur when Vibrio cholerae is found in low densities such as sea water.

Question 42

The purpose of hemimethylated DNA is to block chromosome replication.

Question 43

Natural antibiotics are produced by all bacterial genera.

Question 44

The Par system is analogous to spindle fibers in eukaryotic cells.

Question 45

The activity of MinC and MinD direct whether a bacterial cell will be coccoid or bacillus shaped.

Question 46

In the Caulobacter life cycle, the role of swarmer cells is strictly for reproduction.

Question 47

Both crescentin and MreB play a role in formation of the vibrio-shaped bacterium Caulobacter.

Question 48

Multiple sigma factors are essential to induce the biosynthesis of endospores, consequently a complex regulatory mechanism such as this has a higher chance of mutation leading to incorrect functioning compared to a simple repression mechanism.

Question 49

Plasmids are replicated in Escherichia coli using the Par system.

Question 50

During elongation of a cell during binary fission, small gaps caused by transglycosylases are formed before cell membrane precursors can be inserted.

Question 51

In fast-growing Escherichia coli cells, multiple replication forks of genomic DNA allows binary fission to occur before the genome has been fully duplicated.

Question 52

The spherical shape of Staphylococcus aureus is a result of MreB function.

Question 53

Multiple sigma factors are essential to induce the formation of endospores.

Question 54

Why is the presence of a cell wall significant from a clinical standpoint?

A) All types of cells have a cell wall, and it makes identification of the causative agent of disease difficult.
B) The cell wall protects microorganisms from destruction by the immune system.
C) Animal cells do not have cell walls, so antibiotics that target cell walls can selectively destroy invading microorganisms.
D) Only gram-negative Bacteria have cell walls.

Question 55

Which of the following molecules functions as an intracellular signaling molecule during quorum sensing?

A) acylated homoserine lactones
B) hydrophilic lipids
C) quinones
D) proteorhodopsins

Question 56

Generation of new bacillus-shaped cells starts with one cell elongating and terminates when it splits into two separate bacilli.

Question 57

Antibiotic resistance can develop in a bacterium as a result of spontaneous mutation.

Question 58

Dormancy is a result of all of the following EXCEPT

A) phenotypic heterogeneity.
B) ineffective efflux pumps.
C) TA modules.
D) the stringent response.

Question 59

All members of the genus Pseudomonas respond similarly to c-di-GMP.

Question 60

PopZ plays a critical role in localizing proteins to the cell poles.

Question 61

How might a genetically modified strain of E.coli with a nonfunctional mreB gene compare to E. coli possessing a functional mreB gene?

Question 62

When Mycobacterium tuberculosis is in the dormant state it is still susceptible to antibiotics, but the rate of death is slower.

Question 63

The toxin component of TA modules helps ensure survival during stressful growth conditions.

Question 64

Describe the functions of the FtsZ protein and the Z-ring in bacterial cells.

Question 65

What is the purpose of the MreB protein in bacteria?

Question 66

What role does the Par system play in bacterial cell division?

Question 67

In both cocci as well as rod-shaped cells, new peptidoglycan synthesis occurs in both directions from the central location of the FtsZ ring.

Question 68

Free HipA toxin inhibits transcription.

Question 69

MRSA strains synthesize MecA only in the presence of methicillin or other β-lactam antibiotics.

Question 70

A researcher unexpectedly identified mutant bacteria deficient in the FtsZ protein. Their growth appeared filamentous, and displayed incomplete cell division. Explain the role of the FtsZ protein and how a deficiency would account for this altered growth.

Question 71

Unlike penicillin, methicillin targets an alternative penicillin binding protein called MecA in nonresistant Staphylococcus aureus.

Question 72

Oxygenic phototrophs require the uptake of oxygen for the reactions of photosynthesis.

Question 73

Explain how green fluorescent protein (GFP) could be utilized to determine the role of FtsZ in binary fission in Escherichia coli.

Question 74

Explain the role of CtrA in the formation of swarmer cells in Caulobacter.

Question 75

Explain how FtsZ-type proteins being found in mitochondria and chloroplasts strengthens or weakens the endosymbiosis theory.

Question 76

Antibiotic-sensitive bacteria sometimes produce cells that are transiently resistant to multiple antibiotics.

Question 77

Mobile resistance genes encode enzymes that inactivate an antibiotic by altering its structure.

Question 78

Explain the impact spontaneous mutation of the gene minE in an Escherichia coli bacterium would have on future cell divisions.

Question 79

Persistence is a heritable trait.

Question 80

FtsZ is analogous to the protein tubulin in eukaryotic cells.