Deck 8: Regulation of Gene Expression

Question 1

Regulation of an enzyme's activity occurs

A) translationally.
B) at any point on the enzymatic production pathway.
C) posttranslationally.
D) transcriptionally.

Answer 1

C

Question 2

Enzyme induction occurs

A) when the organism is environmentally stressed.
B) when the substrate is depleted.
C) when the substrate is present.
D) continuously.

Answer 2

C

Question 3

In the tryptophan operon, synthesis of the leader peptide results in

A) termination of transcription of the remainder of the trp operon.
B) augmentation of transcription of the tryptophan structural genes.
C) initiation of transcription of the tryptophan structural genes.
D) none of the above.

Answer 3

A

Question 4

Histones are , so they combine strongly and relatively nonspecifically with DNA.

A) positively charged / negatively charged
B) negatively charged / positively charged
C) positively charged / neutral
D) neutral / negatively charged

Question 5

What is the direct cause of catabolite repression?

A) the synthesis of fi- galactosidase
B) the presence of glucose and lactose in a growth medium
C) binding of CAP to the DNA
D) a cellular deficiency of cyclic AMP

Question 6

Alternative sigma factors in the cell regulate the

A) heat shock response.
B) negative ionic response.
C) electrical gradient response.
D) RNA polymerase response.

Question 7

Arginine in the culture medium

A) has no effect on the enzymes required for the production of arginine.
B) enhances the synthesis of the enzymes required for the production of arginine.
C) neutralizes the enzymes required for the production of arginine.
D) represses the synthesis of the enzymes required for the production of arginine.

Question 8

Protein binding occurs at the site of DNA.

A) histone complex
B) primary supercoil
C) minor groove
D) major groove

Question 9

In enzyme induction, a(n) represses enzyme production.

A) corepressor
B) inducer
C) effector
D) repressor

Question 10

Which of the following is a major phases of the regulation of differentiation in prokaryotes?

A) asymmetric development of two sister cells
B) triggering of the response
C) reciprocal communication between the two differentiating cells
D) all of the above

Question 11

Cyclic AMP is synthesized from ATP by an enzyme called

A) catabolite activator protein (CAP) activase.
B) RNA polymerase.
C) adenylate cyclase.
D) cAMP receptor protein (CRP) receptase.

Question 12

When considering the biological information flow, transcription is usually thought of as the

A) first step.
B) second step.
C) third step.
D) only step, because everything else flows from transcription.

Question 13

Endospore formation in Bacillus subtilis is triggered by adverse external conditions that are monitored by a five sensor kinase system whose mechanism resembles that of

A) a stringent response.
B) chemotaxis regulation.
C) a heat shock response.
D) a two- component regulatory system.

Question 14

In negative control of transcription, how does the presence of an inducer affect transcription?

A) The inducer does not bind to the operator.
B) The inducer binds to the operator.
C) The inducer causes the repressor to bind to the operator.
D) The inducer prevents the repressor from binding to the operator.

Question 15

Regulatory proteins

A) bind to specific DNA sites.
B) regulate transcription.
C) are influenced by small molecules.
D) do all of the above.

Question 16

The promoters of positively controlled operons require activator proteins, because

A) the promoters have nucleotide sequences that bind RNA polymerase weakly, which are not close matches to the consensus sequence.
B) they are needed to bind to the allosteric site of RNA polymerase.
C) RNA polymerase easily recognizes the consensus sequence.
D) they are required to inactivate the repressor proteins.

Question 17

Enzyme repression and induction occur at the level of

A) translation.
B) pretranscription.
C) transcription.
D) posttranslation.

Question 18

Which of the following is necessary for negative control of the tryptophan operon?

A) leader sequence
B) operator
C) promoter
D) all of the above

Question 19

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

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

Question 20

When arginine is added to a culture growing exponentially in a medium without arginine, what occurs?

A) All cellular growth ceases.
B) Growth continues, but the production of enzymes required for the synthesis of arginine increases.
C) Growth continues, but the production of enzymes required for the synthesis of arginine ceases.
D) The cell returns to the lag stage of growth to synthesize the proteins necessary for the metabolism of arginine.

Question 21

Noncoding RNA molecules consist of _ _, , and .

Question 22

The domain frequently found in eukaryotic regulatory proteins that binds to a zinc ion is commonly called the .

Question 23

The nucleotide triggers of the stringent response are and .

Question 24

A cluster of several genes whose expression is under the control of a single operator is called a(n) _ .

Question 25

Effector molecules that influence enzyme synthesis include both _ and _.

Question 26

are RNA molecules that resemble repressors and activators in binding metabolites and regulating gene expression.

Question 27

The genes in Pseudomonas aeruginosa that enable cells to transition from growth in suspension to growth in a biofilm are expressed due to .

Question 28

Most signal transduction pathways in eukaryotes rely on phosphorylation of ,
, and residues of proteins, while those of Bacteria rely on phosphorylation of residues.

Question 29

is a type of control that occurs after the initiation of transcription but before its completion.

Question 30

Regulatory mechanisms that respond to environmental signals by regulating expression of many different genes are called _.

Question 31

Heat shock proteins perform which of the following functions?

A) prevent aggregation of newly synthesized proteins
B) remove denatured or irreversibly aggregated proteins
C) catalyze the correct folding of misfolded proteins
D) all of the above

Question 32

When more than one operon is under the control of a single regulatory protein, these operons are collectively called a(n) .

Question 33

Attenuation occurs in the biosynthetic pathway for phenylalanine in Escherichia coli. Therefore, the leader sequence for this pathway will be rich in which of the following?

A) histidine
B) isoleucine
C) phenylalanine
D) threonine

Question 34

Inverted repeats in DNA are frequently found in the locations where .

Question 35

The two general kinds of protein- nucleic acid interactions are _ and _ .

Question 36

The most frequent way in which regulatory RNA molecules exert their effects is by

A) binding to a repressor and repressing enzyme transcription.
B) signal transduction.
C) acting as an inducer that then binds to an activator protein to allow transcription to proceed.
D) base pairing with other RNA molecules that have regions of complementary sequence.

Question 37

The activity of a protein can be regulated only , while the amount of a protein synthesized can be regulated or _.

Question 38

The syntheses of a variety of unrelated enzymes are inhibited when cells are grown in an environment that contains glucose. This phenomenon is known as and is sometimes referred to as the .

Question 39

The function of a kinase is

A) glycosylation.
B) response regulation.
C) phosphorylation.
D) methylation.

Question 40

Three classes of protein domains that are critical for proper binding of DNA- binding proteins to DNA in both prokaryotes and eukaryotes include _, , and
.

Question 41

Controlling the activity of an enzyme is an inefficient use of the organism's energy.

Question 42

For the CRP protein to bind to the DNA in the promoter region and thus facilitate translation, a sufficiently high level of cyclic AMP must be present.

Question 43

Most DNA- binding proteins interact with DNA in a sequence- specific manner.

Question 44

The phenomenon in which bacterial regulatory pathways are controlled by the density of cells of their own kind is called .

Question 45

Most riboswitches function to control of mRNA, rather than its .

Question 46

Small molecules usually act directly (rather than indirectly) in regulating transcription.

Question 47

When cells experience heat shock, the degradation of sigma factor 32 is inhibited.

Question 48

In the external signal is transmitted to a sensor that transmits the signal to the rest of the regulatory machinery.

Question 49

Enzymes carry out the different biochemical reactions needed for cell growth.

Question 50

During chemotaxis, attractants increase the rate of autophosphorylation whereas repellants decrease this rate.

Question 51

The major means of regulation in prokaryotes occurs posttranslationally.

Question 52

Proteins that bind to DNA can either block or activate transcription.

Question 53

Proteins and RNA molecules that are needed in the cell, at about the same level under all growth conditions, require constitutive expression.

Question 54

Transcriptional regulation is considered negative when an inducer binds to and deactivates a repressor.

Question 55

In the tryptophan operon, translation of the leader peptide regulates transcription of the tryptophan genes downstream and is called attenuation.

Question 56

The regulation of enzyme synthesis is usually a more rapid process than the regulation of enzyme activity.

Question 57

Bacteria are the only microorganisms capable of regulating expression of their genes.

Question 58

In discussing the control of enzyme transcription, it is essential to consider the cell's environment.

Question 59

DNA binding proteins are typically and contain a region called a(n) that interacts specifically with a region of the DNA.

Question 60

Histones are universally present in prokaryotic cells.

Question 61

How is the leucine zipper formed, and what is its function?

Question 62

In considering the function of heat shock proteins, why is it not a surprise that these proteins are both highly conserved and very ancient? Provide your reasoning.

Question 63

Explain why one cell of a pathogenic bacterium by itself typically does not secrete a toxin, despite the species as a whole being characterized as toxin producing.

Question 64

The catabolism of the sugar maltose in Escherichia coli is an example of a system that involves positive regulation.

Question 65

In most cases, the first product of a particular biosynthetic pathway represses the enzymes of the pathway.

Question 66

Why is it unsurprising that two- component regulatory systems are all but absent in bacteria that live at the expense of a host?

Question 67

The lactose operon and the maltose regulon are under the control of global control mechanisms as well as their own specific regulatory systems.

Question 68

Explain the translational attenuation mechanism.

Question 69

In catabolic repression, cells use the least abundant carbon source first.

Question 70

How is transcription in Archaea controlled?

Question 71

Using the tryptophan operon as a model, explain a transcription pause site and the formation of a stem- loop.

Question 72

What is the difference between an operator and a promoter?

Question 73

Regulation of the amount of enzyme synthesized occurs only at the gene level.

Question 74

Describe the basic two- component regulatory system.

Question 75

Explain how the alarmones ppGpp and pppGpp function during amino acid starvation.

Question 76

Explain why cellular cannibalism is beneficial for sporulating Bacillus subtilis.

Question 77

Explain why regulation of enzyme synthesis is more time consuming than regulation of enzymatic activity.

Question 78

As a general rule, any given gene has only one type of control system.

Question 79

Describe the function and the functional components of the maltose regulon system.

Question 80

DNA- binding proteins typically affect translation of a protein.