Deck 10: Molecular Regulation

Question 1

Which form of control is the most rapid?

A) alterations of DNA sequence
B) control of transcription via activators and repressors
C) mRNA stability
D) translational control
E) use of various sigma factors

Answer 1

D

Question 2

A transmembrane sensor kinase protein senses an environmental condition outside __________ bacteria or in the periplasm of a(n) __________ bacteria.

A) Gram-positive; Gram-negative
B) Gram-negative; Gram-positive
C) prokaryotic; eukaryotic
D) prokaryotic; archaean
E) Gram-positive; acid-fast

Answer 2

A

Question 3

Which form of control is the least reversible and most drastic?

A) posttranslational control
B) control of transcription
C) alterations of DNA sequence
D) translational control
E) mRNA stability

Answer 3

C

Question 4

What occurs when an inducer is added to a medium containing an organism with a metabolic pathway controlled by a repressor?

A) The inducer combines with the repressor and activates the repressor.
B) The inducer combines with the repressor and inactivates the repressor.
C) The inducer combines with the substrate and blocks induction.
D) The inducer combines with the substrate and activates induction.
E) The inducer does not combine with, but functions as a chaperone molecule for, the enzyme-substrate complex.

Question 5

When both glucose and lactose are added to the growth medium, Escherichia coli will have a growth curve that:

A) does not change
B) grows slowly and then, halfway through, grows faster
C) grows, levels off, and then grows again
D) grows more slowly than with glucose alone
E) grows more quickly than with glucose alone

Question 6

Symmetry, in terms of DNA binding, usually involves a(n):

A) inverted repeat
B) major groove
C) chaperone
D) mRNA
E) direct repeat

Question 7

Binding of tryptophan to the __________ makes a holorepressor.

A) aporepressor
B) corepressor
C) repressor
D) inducer
E) activator

Question 8

Sets of genes in operons are coordinately regulated by all of the following EXCEPT:

A) protein repressors
B) activators
C) sigma factors
D) small RNAs
E) irreversible changes in the DNA sequence

Question 9

If a gene is always expressed, it is:

A) constitutive
B) inducible
C) repressible
D) derepressible
E) promotable

Question 10

__________ prevent transcription, whereas __________ stimulate transcription.

A) Activators; repressors
B) Inducers; corepressors
C) Corepressors; inducers
D) Regulators; repressors
E) Repressors; activators

Question 11

Transcriptional attenuation is a common regulatory strategy used to control many operons that code for what?

A) amino acid degradation
B) amino acid biosynthesis
C) carbohydrate degradation
D) carbohydrate biosynthesis
E) lipid degradation

Question 12

How many of the gene products of the lactose operon are required for the utilization of lactose to occur?

A) none
B) one
C) two
D) three
E) four

Question 13

The araBAD and araC genes are transcribed in the __________ direction with respect to each other.

A) same
B) opposite
C) forward
D) left
E) right

Question 14

Which of the following is the favored carbon source of Escherichia coli?

A) lactose
B) galactose
C) sucrose
D) glucose
E) fructose

Question 15

In a two-component signal transduction system, a _________ is transferred from a sensor kinase to a _________ in response to an environmental signal.

A) phosphate; sensor domain
B) phosphate; sensor phosphatase
C) phosphate; response regulator
D) magnesium; sensor domain
E) magnesium; response regulator

Question 16

A feature common to all control mechanisms is:

A) quorum sensing
B) phosphorylation cascades
C) ability to sense that something inside or around the cell has changed
D) housekeeping enzymes
E) increased or decreased gene expression

Question 17

When __________ interacts with RNA polymerase, it increases the rate of transcription initiation of the lac operon.

A) LacI protein
B) cAMP receptor protein
C) lactose
D) allolactose
E) glucose

Question 18

In some, but not all, instances, __________ molecules bind RNA transcripts and help or hinder degradation.

A) tsRNA
B) rRNA
C) tRNA
D) sRNA
E) mRNA

Question 19

Finding an inverted repeated sequence within 100-200 bases of a promoter suggests the presence of a __________ binding site.

A) DNA
B) transcriptional regulator
C) RNA
D) ribosome
E) corepressor

Question 20

All of the following typically occur in the presence of high glucose and high lactose concentrations EXCEPT:

A) enzyme II glucose is unphosphorylated
B) cAMP concentrations are low
C) C-reactive protein levels in the cell are low
D) inhibition of LacY activity
E) lactose is kept out of the cell

Question 21

Which of the following is NOT true of phase variation?

A) The orientation of the DNA sequence is inverted.
B) It may help the bacteria avoid the immune system.
C) It can result in a change in microbial appearance.
D) It only occurs in prokaryotes.
E) All are true.

Question 22

The stringent response relies on the production of:

A) pG
B) ppG
C) pppG
D) pGp
E) ppGpp

Question 23

The role of the Hin recombinase is to:

A) recombine specific segments of the DNA of Haemophilus influenzae
B) recombine specifc segments of flagellin genes in Neisseria gonorrhoeae
C) recombine specific segments of MCP genes in Salmonella enterica
D) recombine specific segments of flagellin genes in Salmonella enterica
E) repair damage in DNA

Question 24

The AraC-like regulators share homology with each other at which locations?

A) both their C-terminal end and their N-terminal end
B) neither their C-terminal end nor their N-terminal end
C) their C-terminal end only
D) their N-terminal end only
E) the center

Question 25

If the newly synthesized DNA strand slips back relative to the template strand, one copy of the repeated unit is __________ the growing strand.

A) inserted in
B) deleted from
C) folded over
D) folded under
E) bound to

Question 26

Bacterial systems using an AraC/XylS type regulator include __________ as regulated by __________.

A) a type III secretion system in Pseudomonas; NitR
B) a type III secretion system in Pseudomonas; ExsA
C) a type III secretion system in Pseudomonas; YbtA
D) virulence genes and cholera toxin in Vibrio; TxtR
E) virulence genes and cholera toxin in Vibrio; ExsA

Question 27

Which of the following explains the regulatory activity of sRNA?

A) It codes for a sigma factor.
B) It prevents CRP interaction with RNA polymerase, thereby blocking its access to the promoter.
C) It synthesizes ppGpp.
D) It targets mRNAs for degradation.
E) It creates an attenuator stem loop.

Question 28

__________ RNAs bind to complementary sequences of target transcripts and stimulate or prevent translation.

A) Ribosomal
B) Transfer
C) Messenger
D) Antisense
E) Small

Question 29

The role of a leader sequence is to:

A) directly control transcription
B) determine whether transcription can proceed through the genes in the operon
C) determine whether RNA polymerase can bind
D) terminate transcription
E) direct the looping of the DNA that prevents transcription initiation

Question 30

The stringent response involves all EXCEPT:

A) downregulation of rRNA synthesis
B) downregulation of tRNA synthesis
C) ATP
D) GTP
E) no change in gene expression

Question 31

__________ genes always occur in intergenic regions.

A) tRNA
B) mRNA
C) sRNA
D) rRNA
E) tsRNA

Question 32

The little amount of sigma H that is made at 30°C is __________ by the DnaK/GrpE/DnaJ chaperones.

A) enhanced
B) activated
C) degraded
D) protected
E) folded

Question 33

Some microbes use gene regulation to periodically change their appearance, in a process called:

A) sporulation
B) attenuation
C) regulation
D) activation
E) phase variation

Question 34

When the forespore is first produced, about how much of the chromosome is actually inside the forespore?

A) 10%
B) 20%
C) 30%
D) 40%
E) 50%

Question 35

Phase variation in Salmonella enterica involves:

A) gene inversion
B) chemotaxis
C) outer membrane proteins
D) sRNA
E) slipped-strand mispairing

Question 36

GlnB allows cells to balance glutamine synthetase __________ with its rate of __________.

A) amounts; degradation
B) mRNA; translation
C) mRNA; transcription
D) synthesis; activity
E) activity; synthesis

Question 37

The mechanism behind slipped-strand mispairing is:

A) short repeats allow for slippage of the RNA polymerase during transcription of the affected genes
B) short repeats allow for slippage of DNA polymerase during replication, which leads to an out-of-frame reading sequence
C) an invertible promoter slips into different reading frames
D) the genes coding for lipopolysaccharide in Gram-negative bacteria can be slipped in and out of frame
E) short repeats slip and turn genes off, but they can never be turned back on

Question 38

The AraC regulatory protein turns on transcription in the presence of arabinose in which way?

A) With the addition of arabinose, AraC no longer dimerizes and will form a large loop by binding to araO and aria, and thus can interact with RNA polymerase to permit transcription.
B) The dimer will form a large loop by binding to araO and aria, and thus can interact with RNA polymerase to permit transcription.
C) With the addition, AraC no longer dimerizes and thus can interact with RNA polymerase to permit transcription.
D) It becomes less flexible, so that a monomer can bind to araI₁ and araI₂ and interact with RNA polymerase to permit transcription.
E) It becomes more flexible, so that the dimer can bind to araI₁ and araI₂ and interact with RNA polymerase to permit transcription.

Question 39

Which of the following is NOT true of sRNA genes?

A) They have a ribosomal-binding site.
B) They occur between genes.
C) They share homology between related species.
D) They can act as antisense RNAs.
E) Their gene product was "Molecule of the Year" in 2002.

Question 40

Which of the following is a second messenger that helps to regulate biofilm production?

A) ppGpp
B) ATP
C) cAMP
D) cGMP
E) cdiGMP

Question 41

Which of the following statements is true concerning the use of cyclic di-GMP as a second messenger?

A) It activates the expression of flagellin genes and thus enhances motility.
B) It is found in all microbes: bacteria, archaea, and eukaryotic microbes.
C) It is produced by the action of diguanylate cyclase.
D) It decreases in level as biofilm is produced.
E) Phosphodiesterase can convert GMP to cyclic di-GMP.

Question 42

Describe what happens to the lac operon in the presence of both lactose and glucose.

Question 43

Which of the following is NOT a process regulated via quorum sensing?

A) pathogenesis of Pseudomonas infection in a cystic fibrosis patient
B) antibiotic production by Streptomyces
C) bioluminescence by Vibrio
D) utilization of lactose by Escherichia coli
E) exotoxin production by Staphylococcus

Question 44

Many bacteria produce some type of homoserine lactone for quorum sensing, yet some Gram-positive bacteria will produce ________________ for this same purpose.

A) antibiotics
B) peptides
C) furanosyl borate diester
D) cyclic di-GMP
E) ppGpp

Question 45

Glucose transport into the cell brings about a phenomenon known as inducer exclusion.
Describe how this functions with respect to the lac operon.

Question 46

All the cell's expressed RNAs are collectively referred to as the cell's:

A) genome
B) transcriptome
C) proteome
D) holoenzyme
E) ORF

Question 47

How is DNA sequence analysis used to study DNA protein binding?

Question 48

What is diauxic growth and why does it occur?

Question 49

Which molecule is used for hybridization to DNA bound on a DNA microchip?

A) DNA
B) RNA
C) mRNA
D) cDNA
E) any of the above

Question 50

Explain the process of attenuation in regulating transcription of the tryptophan operon.

Question 51

How is repression of biosynthetic pathways different than repression of a catabolic pathway? Why does repression of these two types of pathways work differently?

Question 52

In terms of controlling chemotaxis, the proteins involved control chemotaxis in which way?

A) They control which form of flagellin is expressed.
B) They change the direction of the flagella from counterclockwise to clockwise and back.
C) They promote longer "tumbles" when a chemoattractant is present.
D) They increase the phosphorylation of CheY so that there are more counterclockwise flagella.
E) They respond to demethylation of methyl-accepting chemotaxis proteins to bring about longer runs.

Question 53

In the regulation of chemotaxis, proteins are modified in which of the following ways?

A) phosphorylations
B) methylation
C) feedback inhibition
D) phosphorylation and methylation
E) feedback inhibition, phosphorylation, and methylation

Question 54

Explain a way that organisms sense and respond to their environment.

Question 55

Explain how a repressor protein works with respect to a biosynthetic operon.

Question 56

Integrated circuits are involved in all of the following EXCEPT:

A) controlling chemotactic activities of a cell
B) coupling the genetic and biochemical control of a metabolic pathway
C) timing the events of a developmental cycle
D) having an influence on nitrogen metabolism
E) specifically inverting the flagellin genes

Question 57

The AraC regulator both activates and represses transcription of the genes involved in arabinose catabolism. How is this system more advantageous to a cell than a simpler repressor system like that used on the lac operon?

Question 58

Describe the function of prokaryotic activator proteins.

Question 59

Which of the following can be used to study the bacterial proteome?

A) DNA microarrays
B) pyrosequencing
C) two-dimensional gels and mass spectrometry
D) green fluorescent protein
E) networking with nanotubes

Question 60

A quorum-sensing gene system requires the accumulation of a secreted small molecule called a(n):

A) autoinducer
B) activator
C) repressor
D) inducer
E) corepressor

Question 61

Explain how small, untranslated RNAs (sRNAs) regulate iron uptake and iron storage.

Question 62

Explain the process of bioluminescence in Allivibrio fischeri. How is this an example of a mutualistic relationship?

Question 63

Quorum sensing plays a role in interspecies communications. Describe the relationship between green seaweed Enteromorpha and Vibrio anguillarum bacterial cells in biofilms, and explain how Escherichia coli was used to understand this interaction.

Question 64

What does the gene inversion in Salmonella enterica accomplish with respect to its course of infection? Briefly describe how this mechanism works.

Question 65

How is sigma H degradation controlled by temperature, and why is this important to the cell?

Question 66

Explain what happens to motility when a chemoattractant is added to bacterial cells.

Question 67

Briefly explain the two-dimensional gels electrophoresis. What is the procedure used to determine, and why are both dimensions necessary?

Question 68

What happens when strand slippage occurs on the template or the newly synthesized DNA strand? How does Neisseria gonorrhoeae use slipped-strand mispairing to its advantage?

Question 69

The stringent response down-regulates rRNA synthesis. Does it similarly down-regulate ribosomal protein synthesis?

Question 70

During the process of endospore formation, different sigma factors are active in the mother cell and forespore. How is this possible, and why is it important?