Deck 13: Microbial Genetics Regulation of Gene Expression

Question 1

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
D) all of the choices
E) coli.

Answer 1

D

Question 2

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).

Answer 2

A

Question 3

__________ alter repressor proteins thereby increasing the rate of transcription initiation.

A) Inducers
B) Corepressors
C) Effectors
D) Modulators

Answer 3

A

Question 4

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.

Question 5

Bacteria, Archaea, and Eukarya differ in both their genome structure as well as in the steps required to complete gene expression.

Question 6

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.

Question 7

Two-component signal transduction systems are found in the Bacteria, but not in Archaea.

Question 8

If a set of genes is repressed in the presence of the controlling substance, it is referred to as __________ control.

Question 9

When there is no arabinose available in the environment, the AraC protein acts as a(n) ______________ for the
E. coli ara operon.

Question 10

______________ is used to control transcription of some anabolic pathways involved in amino acid biosynthesis.

A) Attenuation
B) Catabolite repression
C) Induction
D) All of the choices

Question 11

When arabinose is present in the environment, the AraC protein acts as a(n) ______________ for the
E. coli ara operon.

Question 12

The real inducer for the
E. coli lac operon is allolactose produced by the action of permease on lactose.

Question 13

__________ activate repressor proteins thereby decreasing the synthesis of certain enzymes.

A) Inducers
B) Corepressors
C) Effectors
D) Modulators

Question 14

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

Question 15

The binding of arabinose to the AraC protein allows it to form a loop in the DNA upstream of the ara operon promoter.

Question 16

In two component regulatory systems, the response regulator typically receives a ____________ from the sensor kinase when it has been activated.

A) pyruvate group
B) phosphoryl group
C) acetyl group
D) methyl group

Question 17

If a set of genes is induced in the presence of the controlling substance, it is referred to as __________ control.

Question 18

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.

Question 19

The

A) one
B) two
C) three
D) four
E) coli lac operon has ________ operator sequences.

Question 20

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

Question 21

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

Question 22

Enzymes that are expressed at a constant level all the time are said to be:

A) inducible.
B) repressible.
C) constitutive.
D) attenuated.

Question 23

The terminator versus anti-terminator function of the T box-based riboswitch used by Gram-positive 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

Question 24

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 occlusion of

A) the promoter
B) the attenuator
C) the Shine-Delgarno sequence
D) the AUG start codon

Question 25

What is the key factor determining whether or not attenuation will occur when transcription of the

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
E) coli trp operon has been initiated?

Question 26

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

Question 27

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

Question 28

Small RNAs that regulate translation by binding to the leader region of mRNAs are called antisense RNAs.

Question 29

Posttranslational regulation occurs after a protein has been synthesized, and can occur by

A) allosteric control
B) feedback inhibition
C) covalent modification
D) allosteric control and covalent modification are both means of regulation after translation is complete

Question 30

What term describes a set of genes that is controlled by a common regulatory protein?

A) codon
B) regulon
C) transcription
D) operon

Question 31

Acylhomoserine lactones used in quorum sensing regulate their own synthesis by a(n) ____________ system.

A) riboswitch
B) antisense
C) catabolite repression
D) autoinduction

Question 32

The site on the DNA to which a repressor protein binds is the __________.

A) operon
B) operator
C) promoter
D) regulator

Question 33

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

Question 34

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

Question 35

Most

A) CAP
B) MicF
C) Hfq
D) none of the choices
E) coli antisense RNAs work with a protein called ______ to regulate their target mRNAs.

Question 36

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

Question 37

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.

Question 38

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.

Question 39

The standard or housekeeping sigma factor used most often by

A) 70
B) 32
C) S
D) E
E) coli RNA polymerase under normal growth conditions is called sigma ___.

Question 40

____________ is used to measure the amount of a chemoattractant encountered over time.

Question 41

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

Question 42

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.

Question 43

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.

Question 44

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

Question 45

Gene regulation during sporulation in Bacillus subtilis involves BOTH temporal and spatial control.

Question 46

During the early stages of sporulation in Bacillus subtilis, ________ is active in the forespore and ________ is active in the mother cell.

A) $\sigma$ ^E; $\sigma$ ^F
B) $\sigma$ ^K; $\sigma$ ^F
C) $\sigma$ ^F; $\sigma$ ^K
D) $\sigma$ ^F; $\sigma$ ^E

Question 47

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.

Question 48

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.

Question 49

In eukaryotes, transcription factors that function as repressors bind regulatory sites called _____________.

Question 50

The regulation of gene expression in the Archaea is totally different than the regulation of gene expression in Bacteria.

Question 51

A collection of genes or operons controlled by a common regulatory protein is called a(n) ___________ .

Question 52

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.

Question 53

In eukaryotes, transcription factors that function as activators bind regulatory sites called _____________.

Question 54

In eukaryotes, some small RNAs are important structural components of the

A) ribosome.
B) endoplasmic reticulum.
C) spliceosome.
D) eucaryotes do not utilize small RNAs.