Deck 14: Control of Gene Expression

Question 1

Which of the following components of an operon is a molecule of DNA?

A)repressor
B)lactose
C)mRNA
D)operator

Answer 1

D

Question 2

Which of the following is a key difference between eukaryotic and prokaryotic genomes?

A)Physical separation of transcription and translation occurs in eukaryotes, but no separation occurs in prokaryotes.
B)Genes are arranged in order in eukaryotes, but the order is random in prokaryotes.
C)Near simultaneous transcription and translation occurs in eukaryotes, but they are strictly sequential in prokaryotes.
D)Gene expression is highly regulated in eukaryotes, but there is a lack of control of gene expression in prokaryotes.

Answer 2

A

Question 3

Where does RNA polymerase first bind to on the E. coli lac operon?

A)to the transcription initiation site
B)to the lacI repressor
C)to the promoter
D)to the operator

Answer 3

C

Question 4

Suppose that an E. coli has a mutation in its lac operon such that the Lac repressor could NOT bind the operator, even in the absence of lactose. What would be the result in terms of the function of the operon?

A)The lac operon would be transcribed, but at a high level.
B)The lac operon would be expressed only when lactose was present.
C)There would be no real impact on lac operon expression.
D)The lac operon would be transcribed, but at a low level.

Question 5

What is the default state of a repressible operon such as the trp operon?

A)normal transcription
B)no transcription
C)low level transcription
D)high level transcription

Question 6

Suppose the lacI repressor gene is permanently silenced by a mutation. What would be the impact on the function of the lac operon?

A)There would be no real impact on lac operon expression.
B)The lac operon would be transcribed, but at a high level.
C)The lac operon would be expressed only when lactose was present.
D)The lac operon would be transcribed, but at a low level.

Question 7

Where is the Trp repressor gene located?

A)just upstream of the trp operon
B)on a region of the chromosome quite distant from the trp operon
C)just downstream of the trp operon
D)adjacent to the Lac repressor gene9

Question 8

Which of the following proteins binds to the operator in the operon model?

A)DNA polymoerase
B)RNA polymerase
C)a regulatory protein
D)lactose

Question 9

What does the presence of lactose allow in the E. coli lac operon?

A)dissociation of the Lac repressor from the promoter
B)dissociation of the Lac repressor from the operator
C)binding of the Lac repressor to the operator
D)binding of the Lac repressor to glucose

Question 10

Genes in operons are transcribed in such a way as to share which of the following molecules?

A)mRNA
B)tRNA
C)protein
D)ribosome

Question 11

What is the essential molecular difference that distinguishes cell types?

A)presence or absence of tissues
B)presence or absence of genes
C)presence or absence of specific introns
D)presence or absence of products resulting from expression of genes

Question 12

Which term refers to a cluster of genes transcribed into a single mRNA unit in the operon model?

A)alpha genes
B)mRNA cluster
C)gene group
D)transcription unit

Question 13

In catabolite repression, what is indicated by high levels of cAMP?

A)low lactose
B)low glucose
C)high lactose
D)high glucose

Question 14

What is the primary distinction between different nucleated cells in a developing zygote?

A)the expression of a gene or group of genes
B)the genetic code of each cell
C)the number of chromosomes present in the nucleus
D)the expression of housekeeping genes

Question 15

Which of the following best explains why E. coli shuts down the trp operon if tryptophan is available in the environment?

A)It does not shut down the trp operon, it only lowers the level of trp operon activity.
B)The trp operon encodes genes that export tryptophan from the cell; if tryptophan already occurs in the environment, further export is not necessary.
C)Synthesizing an amino acid takes energy, so it is a waste of energy to make something that is already available.
D)Environmental tryptophan is of higher quality than what the E. coli can make itself.

Question 16

Suppose that a strain of E. coli containing a mutant lac operon is discovered. Also suppose that the mutant operon is normal in terms of its regulation, but the lacY gene produces a defective protein. Which metabolic function will be impaired in this bacterium?

A)transport of lactose into the cell
B)transacetylase
C)binding of the repressor to the operator
D)conversion of lactose into monosaccharides

Question 17

Which of the following best describes the general strategy of metabolic gene regulation in prokaryotes?

A)Genes are always on for early steps in the pathway, but genes for later steps are generally off.
B)Genes are turned on and off as conditions change.
C)Genes are independently regulated.
D)Genes are always on so the bacteria can respond rapidly to changing conditions.

Question 18

Suppose that you observe a mutant E. coli in which CAP is always inactive. In the presence of lactose and low levels of glucose, what would you expect the gene expression from this mutant's lac operon to be?

A)inactive
B)normal
C)greatly reduced
D)overactive

Question 19

What is the single most important stage when regulating eukaryotic gene expression?

A)RNA interference
B)translational regulation
C)degradation of mRNA
D)initiation of transcription

Question 20

Why do prokaryotic organisms tend to undergo rapid and reversible alterations in their genes?

A)They are not as advanced.
B)They are small.
C)They are simple.
D)They grow quickly.

Question 21

Which of the following determines the types of mRNA that are available to ribosomes?

A)translational regulation
B)posttranslational regulation
C)transcriptional regulation
D)posttranscriptional regulation

Question 22

How are the vast majority of proteins expressed early in an animal's development?

A)They are translated from pre-existing mRNAs present in the unfertilized egg.
B)They are translated from pre-existing mRNAs delivered by the sperm that fertilized an egg.
C)They are transcribed and translated from the unfertilized egg's DNA post-fertilization.
D)They are translated from mRNAs that were transcribed from the zygote's DNA in the first three rounds of cell division.

Question 23

Which of the following is a key regulatory event for regulating transcription initiation?

A)controlling the transition between the inactive and active states of chromatin in the region of H2B histone
B)controlling the transition between the inactive and active states of chromatin in the region of a promoter
C)controlling the transition between the inactive and active states of chromatin in the region of introns
D)controlling the transition between the inactive and active states of chromatin in the region of exons

Question 24

Which type of RNA is transcribed in the nucleus, folded, cleaved by Dicer protein, and is then bound to a target molecule of mRNA?

A)an mRNA that never received its poly(A) tail
B)miRNA
C)an mRNA that was not properly capped
D)siRNA

Question 25

What happens to a DNA promoter sequence when it is methylated?

A)It is temporarily silenced because the methyl group can be removed.
B)It is temporarily transcribed because the methyl group can be removed.
C)It is perpetually transcribed because the methyl group can never be removed.
D)It is permanently silenced because the methyl group can never be removed.

Question 26

Which of the following are the regulatory proteins that play a role in a positive regulatory system that controls the expression of one or more genes?

A)introns
B)exons
C)activators
D)enhancers

Question 27

Which of the following describes the role of acetylation during the chromatin remodelling that accompanies gene expression?

A)It adds an acetyl group (CH₃CH₂-) to the DNA of a promoter sequence.
B)It adds an acetyl group (CH₃CO-) to the histone protecting the promoter region of a gene.
C)It adds an acetyl group (CH₃CO-) to the cytosine nucleotides of DNA.
D)It adds an acetyl group (CH₃CO-) to the histone protecting the transcription unit of a gene.

Question 28

Which of the following determines which genes are transcribed?

A)posttranscriptional regulation
B)transcriptional regulation
C)translational regulation
D)posttranslational regulation

Question 29

Which of the following is the function of a coactivator?

A)It unwinds the promoter DNA, allowing transcription to begin.
B)It recognizes and binds to the TATA box of a protein-coding gene's promoter.
C)It binds to the promoter proximal elements to stimulate transcription initiation.
D)It forms a bridge between the activators at the enhancer and the proteins at the promoter.

Question 30

What is the name of the process that displaces the acetylated nucleosomes in the promoter region from the DNA, or moves them along the DNA away from the promoter?

A)translation
B)promoter remodelling
C)transcriptional regulation
D)chromatin remodelling

Question 31

How does methylation regulate transcription?

A)via the addition of a methyl group to cysteine bases of DNA
B)via the addition of a methyl group to cysteine residues on RNA polymerase II
C)via the addition of a methyl group to cytosine residues on RNA polymerase II
D)via the addition of a methyl group to cytosine bases of DNA

Question 32

Which of the following determines the availability of finished proteins?

A)translational regulation
B)transcriptional regulation
C)posttranscriptional regulation
D)posttranslational regulation

Question 33

Where does the first general transcription factor bind to?

A)site where transcription starts
B)TATA box
C)activator
D)enhancer

Question 34

Suppose that you are asked to locate some mRNA masking proteins, and are given two rabbits-one male and one female-to use as your cell sources. Also suppose that you decide to do some needle biopsies of one particular tissue, and to extract the masking proteins. Which tissues or organ samples should you collect for analysis?

A)skin cells
B)testes
C)liver cells
D)ovaries

Question 35

Why can steroid hormones trigger gene expression in a select number of different cells?

A)because only target cells allow the steroid hormone to cross the plasma membrane
B)because only the target cells have a steroid hormone response element encoded in their DNA
C)because only the target cells have the correct coactivator
D)because only the target cells have a nucleus

Question 36

Which of the following determines the rate at which proteins are made?

A)translational regulation
B)transcriptional regulation
C)posttranslational regulation
D)posttranscriptional regulation

Question 37

What is one function of the 5? UTR (untranslated region) of mRNA?

A)to decrease the half-life of mRNA
B)to extend the half-life of mRNA
C)to stabilize the mRNA structure
D)to control the half-life of mRNA

Question 38

To which portion of the DNA does a steroid hormone receptor bind?

A)a response element
B)an enhancer
C)a gene promoter
D)an operator

Question 39

Which element(s) does RNA polymerase II bind to?

A)transcription factors bound to the promoter
B)free-floating transcription factors
C)TATA box
D)promoter sequence

Question 40

Which of the following is the correct order in the regulation of gene expression in eukaryotes?

A)transcriptional regulation ? posttranscriptional regulation ? translational regulation ? posttranslational regulation
B)translational regulation ? posttranslational regulation ? transcriptional regulation ? posttranscriptional regulation
C)posttranscriptional regulation ? transcriptional regulation ? translational regulation ? posttranslational regulation
D)posttranscriptional regulation ? transcriptional regulation ? posttranslational regulation ? and translational regulation

Question 41

Eukaryotic genes are organized into operons.

Question 42

What form must an mRNA assume in order to be targeted by miRNAs for degradation?

A)a double-stranded form
B)a nuclear form
C)a single-stranded form
D)a stem-loop form

Question 43

An operator and transcription unit are called an operon.

Question 44

Eukaryotic genes consist of protein-coding sequences and adjacent regulatory sequences.

Question 45

Which statement refers to genomic imprinting?

A)An allele of a given gene is spliced during gametogenesis.
B)An allele of a given gene is enhanced during gametogenesis.
C)An allele of a given gene is activated during gametogenesis.
D)An allele of a given gene is silenced during gametogenesis.

Question 46

What is the role of a tumour suppressor protein in a cell?

A)to promote cell division of abnormal cells
B)to slow or halt cell division in abnormal cells
C)to trigger DNA replication in preparation for cell division
D)to promote cell division of healthy cells

Question 47

Pepsin, a digestive enzyme that degrades proteins in the stomach, is synthesized as pepsinogen and converted to active pepsin in the stomach by the removal of several amino acids. What is the activation of pepsin an example of?

A)posttranslational regulation
B)transcriptional regulation
C)translational regulation
D)posttranscriptional regulation

Question 48

Which types of proteins do proto-oncogenes tend to be?

A)protein phosphorylases
B)membrane-associated proteins
C)extracellular receptors and protein kinases
D)intracellular receptors

Question 49

Which type of RNA is produced from genes that come from outside the cell?

A)mRNA
B)miRNA
C)tRNA
D)siRNA

Question 50

What happens to a protein when it is tagged with ubiquitin?

A)The protein is sent to the nucleus.
B)The ubiquitin enzyme degrades the protein.
C)The protein is sent to the proteasome and is hydrolyzed to amino acids.
D)The ubiquitin unfolds the protein.

Question 51

Acetylation is irreversible.

Question 52

The DNA that encodes siRNA is NOT normally found in the nucleus.

Question 53

RNAi is a key regulator of transcription.

Question 54

When DNA is imprinted, the methylation pattern is preserved.

Question 55

Any gene could, theoretically, be specifically silenced by RNAi.

Question 56

Each steroid hormone can bind to its own steroid hormone response unit (SHRU) but NOT to the SHRU associated with other steroid hormones.

Question 57

Many eukaryotic operons are subject to numerous regulatory mechanisms.

Question 58

Which of the following is a characteristic of normal cells relative to cancer cells?

A)dedifferentiation
B)differentiation
C)uncontrolled growth
D)lack of tumour suppressor proteins

Question 59

Which of the following is part of posttranslational modification?

A)the chemical modification of proteins
B)cleavage of poly(A) tails from mRNA
C)chromatin remodelling
D)the binding of miRNAs to mRNA

Question 60

Which of the following genes encode proteins that generally stimulate cell division in normal cells?

A)proto-suppressor genes
B)proto-oncogenes
C)oncogenes
D)tumour suppressor genes

Question 61

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
activator

Question 62

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
inducer

Question 63

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
benign

Question 64

When comparing gene regulation in prokaryotes to that in eukaryotes, which is better? Justify your answer.

Question 65

Identify each labelled part of this illustration of eukaryotic DNA.
RNA polymerase

Question 66

The default state for the lac operon is off, while the default state for the trp operon is on. Explain this contradiction and the mechanism of control via the repressor proteins.

Question 67

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
chromatin remodelling

Question 68

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
malignant

Question 69

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
transcriptional regulation

Question 70

Identify each labelled part of this illustration of eukaryotic DNA.
enhancer

Question 71

A direct correlation exists between the level of translation and the length of a poly(A) tail.

Question 72

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
silencing

Question 73

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
siRNA

Question 74

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
miRNA

Question 75

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
repressor

Question 76

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
operon

Question 77

Compare and contrast DNA methylation to histone acetylation.

Question 78

A benign tumour is usually NOT life-threatening.

Question 79

Explain how combinatorial gene regulation allows eukaryotes to coordinate the expression of different genes very efficiently.

Question 80

Match each term with its definition.
a.regulatory protein that activates the expression of an operon's genes
b.interfering RNA molecules originally encoded by nuclear DNA
c.process of controlling the expression of genes that takes place at the DNA level
d.regulatory protein that prevents an operon's genes from being expressed
e.inhibition of transcription via DNA methylation
f.interfering RNA molecules associated with some viral life cycles
g.tumour comprising cells that invade and disrupt the surrounding tissues
h.increases expression of an operon's genes
i.cluster of prokaryotic genes and their associated DNA regulatory sequences
j.tumour comprising undifferentiated cells that stay together in a single mass
k.spread of malignant cells through the blood or lymphatic system
l.
removes a nucleosome from DNA to expose a promoter
metastasis