Biology for AP Courses

Julianne Zedalis, John Eggebrecht

Chapter 16

Gene Regulation - all with Video Answers

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Chapter Questions

Problem 1

Control of gene expression in eukaryotic cells occurs at which level(s)?
a. only the transcriptional level
b. epigenetic and transcriptional levels
c. epigenetic and transcriptional and translational levels
d. epigenetic and transcriptional, translational, and post-translational levels

Nalvi Duro

Nalvi Duro

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Problem 2

What do figures X and Y in the graphic illustrate?
a. Transcription and translation in a eukaryotic cell (figure X) and a prokaryotic cell (figure Y).
b. Transcription and translation in a prokaryotic cell (figure X) and a eukaryotic cell (figure Y).
c. Transcription in a eukaryotic cell (figure X) and translation in a prokaryotic cell (figure Y).
d. Transcription in a prokaryotic cell (figure X) and translation in a eukaryotic cell (figure Y)

Eric Goldman

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Problem 3

If glucose is absent but lactose is present, the lac operon will be:
a. activated
b. repressed
c. partially activated
d. mutated

Nalvi Duro

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Problem 4

.What would happen if the operator sequence of the lac operon contained a mutation that prevented the repressor protein from binding the operator?
a. In the presence of lactose, the lac operon will not be transcribed.
b. In the absence of lactose, the lac operon will be transcribed.
c. The cAMP-CAP complex will not increase RNA synthesis.
d. The RNA polymerase will not bind the promoter.

Eric Goldman

Numerade Educator

Problem 5

What would happen if the operator sequence of the trp operon contained a mutation that prevented the repressor protein from binding to the operator?
a. In the absence of tryptophan, the genes trpA-E will not be transcribed.
b. In the absence of tryptophan, only genes trpE and trpD will be transcribed.
c. In the presence of tryptophan, the genes trpA-E will be transcribed.
d. In the presence of tryptophan, the trpE gene will not be transcribed.

Nalvi Duro

Numerade Educator

Problem 6

What are epigenetic modifications?
a. the addition of reversible changes to histone proteins and DNA
b. the removal of nucleosomes from the DNA
c. the addition of more nucleosomes to the DNA
d. mutation of the DNA sequence

Eric Goldman

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Problem 7

Which of the following statements about epigenetic regulation is false?
a. Histone protein charge becomes more positive when acetyl groups are added.
b. DNA molecules are modified within CpG islands.
c. Methylation of DNA and histones causes nucleosomes to pack tightly together.
d. Histone acetylation results in the loose packing of nucleosomes.

Nalvi Duro

Numerade Educator

Problem 8

Which of the following is true of epigenetic changes?
a. They only allow gene expression.
b. They allow movement of histones.
c. They change the DNA sequence.
d. They are always heritable.

Eric Goldman

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Problem 9

The binding of what is required for transcription start?
a. a protein
b. DNA polymerase
c. RNA polymerase
d. a transcription factor

Nalvi Duro

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Problem 10

What would be the outcome of a mutation that prevented DNA binding proteins from being produced?

a. decreased transcription because transcription factors would not bind to transcription binding sites
b. decreased transcription because enhancers would not be able to bind to transcription factors
c. increased transcription because repressors would not be able to bind to promoter regions
d. increased transcription because RNA polymerase would be able to increase binding to promoter regions

Eric Goldman

Numerade Educator

Problem 11

What will result from the binding of a transcription factor to an enhancer region?
a. decreased transcription of an adjacent gene
b. increased transcription of a distant gene
c. alteration of the translation of an adjacent gene
d. initiation of the recruitment of RNA polymerase

Nalvi Duro

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Problem 12

Which of the following are involved in posttranscriptional control?
a. control of RNA splicing
b. ubiquitination
c. proteolytic cleavage
d. phosphorylation

Eric Goldman

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Problem 13

Gene A is thought to be associated with color blindness. The protein corresponding to gene A is isolated. Analysis of the protein recovered shows there are actually two different proteins that differ in molecular weight that correspond to gene A. What is one reason why there may be two proteins corresponding to the gene?
a. One protein had a 5’ cap and a poly-A tail in its mRNA, and the other protein did not.
b. One protein had a 5’ UTR and a 3’ UTR in its RNA, and the other protein did not.
c. The gene was alternatively spliced.
d. The gene produced mRNA molecules with differing stability.

Nalvi Duro

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Problem 14

Binding of an RNA binding protein will change the stability of the RNA molecule in what way?
a. increase
b. decrease
c. neither increase nor decrease
d. either increase or decrease

Eric Goldman

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Problem 15

A mutation in the 5’UTR that prevents any proteins from binding to the region will:
a. increase or decrease the stability of the RNA molecule
b. prevent translation of the RNA molecule
c. prevent splicing of the RNA molecule
d. increase or decrease the length of the poly-A tail

Alyssa Mcalarney

Alyssa Mcalarney

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Problem 16

Post-translational modifications of proteins can affect which of the following?
a. mRNA splicing
b. 5’capping
c. 3’polyadenylation
d. chemical modifications

Eric Goldman

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Problem 17

A mutation is found in eIF-2 that impairs the initiation of translation. The mutation could affect all but one of the following functions of eIF-2. Which one would not be affected?
a. The mutation prevents eIF-2 from binding to RNA.
b. The mutation prevents eIF-2 from being phosphorylated.
c. The mutation prevents eIF-2 from binding to GTP.
d. The mutation prevents eIF-2 from binding to the 40S ribosomal subunit

Nalvi Duro

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Problem 18

The addition of a ubiquitin group to a protein does what?
a. increases the stability of the protein
b. decreases translation of the protein
c. increases translation of the protein
d. marks the protein for degradation

Eric Goldman

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Problem 19

What are cancer-causing genes called?
a. transformation genes
b. tumor suppressor genes
c. oncogenes
d. protooncogenes

Nalvi Duro

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Problem 20

Targeted therapies are used in patients with a certain gene expression pattern. A targeted therapy that prevents the activation of the estrogen receptor in breast cancer would be beneficial to what type of patient?
a. patients who express the EGFR receptor in normal cells
b. patients with a mutation that inactivates the estrogen receptor
c. patients with over-expression of ER alpha in their tumor cells
d. patients with over-expression of VEGF, which helps in tumor angiogenesis

Eric Goldman

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Problem 21

In a new cancer treatment, a cold virus is genetically modified so that it binds to, enters, and is replicated in cells, causing them to burst. The modified cold virus cannot replicate when wildtype p53 protein is present in the cell. How does this treatment treat cancer without harming healthy cells?
a. The modified virus only infects and enters cancer cells.
b. The modified virus replicates in normal and cancer cells.
c. The modified virus only infects and enters normal cells.
d. The modified virus replicates only in cancer cells.

Nalvi Duro

Numerade Educator

Problem 22

A drug designed to switch silenced genes back on in cancer cells would result in what?
a. prevent methylation of DNA and deacetylation of histones
b. prevent methylation of DNA and acetylation of histones
c. prevent deacetylation of DNA and methylation of histones
d. prevent acetylation of DNA and demethylation of histones

Eric Goldman

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Problem 23

What are positive cell-cycle regulators that can cause cancer when mutated called?
a. transformation genes
b. tumor suppressor genes
c. oncogenes
d. mutated genes

Nalvi Duro

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Problem 24

Which best distinguishes prokaryotic and eukaryotic cells?
a. Prokaryotes possess a nucleus whereas eukaryotes do not, but eukaryotes show greater
compartmentalization that allows for greater regulation of gene expression.
b. Eukaryotic cells contain a nucleus whereas prokaryotes do not, and eukaryotes show greater
compartmentalization that allows for greater regulation of gene expression.
c. Prokaryotic cells are less complex and perform highly-regulated gene expression whereas
eukaryotes perform less-regulated gene expression.
d. Eukaryotic cells are more complex and perform less-regulated gene expression whereas
prokaryotic cells perform highly-regulated gene expression.

Amrita Narasimhan

Amrita Narasimhan

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Problem 25

Which statement is correct regarding the distinction between prokaryotic and eukaryotic gene expression?
a. Prokaryotes regulate gene expression at the level of transcription whereas eukaryotes regulate at
multiple levels including epigenetic, transcriptional and translational.
b. Prokaryotes regulate gene expression at the level of translation whereas eukaryotes regulate at the level of transcription to manipulate protein levels.
c. Prokaryotes regulate gene expression with the help of repressors and activators whereas eukaryotes regulate expression by degrading mRNA transcripts, thereby controlling protein
levels.
d. Prokaryotes control protein levels using epigenetic modifications whereas eukaryotes control protein levels by regulating the rate of transcription and translation.

Nalvi Duro

Numerade Educator

Problem 26

All the cells of one organisms share the genome. However, during development, some cells develop into
skin cells while others develop into muscle cells. How can the same genetic instructions result in two different cell types in the same organism? Thoroughly explain your answer.

Eric Goldman

Numerade Educator

Problem 27

Which of the following statements describes prokaryotic transcription of the lac operon?
a. When lactose and glucose are present in the medium, transcription of the lac operon is
induced.
b. When lactose is present but glucose is absent, the lac operon is repressed.
c. Lactose acts as an inducer of the lac operon when glucose is absent.
d. Lactose acts as an inducer of the lac operon when glucose is present.

Nalvi Duro

Numerade Educator

Problem 28

The lac operon consists of regulatory regions such as the promoter as well as the structural genes lacZ, lacY, and lacA, which code for proteins involved in lactose metabolism. What would be the outcome of a mutation in one of the structural genes of the lac operon?
a. Mutation in structural genes will stop transcription.
b. Mutated lacY will produce an abnormal $\beta$ galactosidase protein.
c. Mutated lacA will produce a protein that will transfer an acetyl group to $\beta$ galactosidase.
d. Transcription will continue but lactose will not be metabolized properly.

Eric Goldman

Numerade Educator

Problem 29

In some diseases, alteration to epigenetic modifications turns off genes that are normally expressed.
Hypothetically, how could you reverse this process to turn these genes back on?

Alyssa Mcalarney

Alyssa Mcalarney

Numerade Educator

Problem 30

Flowering Locus C (FLC) is a gene that is responsible for flowering in certain plants. FLC is expressed in new seedlings, which prevents flowering. Upon exposure to cold temperatures, FLC expression decreases and the plant flowers. FLC is regulated through epigenetic modifications. What type of epigenetic modifications are present in new seedlings and after cold exposure?
a. In new seedlings, histone acetylations are present; upon cold exposure, methylation occurs.
b. In new seedlings, histone deacetylations are present; upon cold exposure, methylation occurs.
c. In new seedlings, histone methylations are present; upon cold exposure, acetylation occurs.
d. In new seedlings, histone methylations are present; upon cold exposure, deacetylation occurs

Eric Goldman

Numerade Educator

Problem 31

A mutation within the promoter region can alter gene transcription. Describe how this can happen.
a. Mutated promoters decrease the rate of transcription by altering the binding site for the transcription factor.
b. Mutated promoters increase the rate of transcription by altering the binding site for the transcription factor.
c. Mutated promoters alter the binding site for transcription factors to increase or decrease the
rate of transcription.
d. Mutated promoters alter the binding site for transcription factors and thereby cease transcription of the adjacent gene.

Nalvi Duro

Numerade Educator

Problem 32

What could happen if a cell had too much of an activating transcription factor present?
a. The transcription rate would increase, altering cell function.
b. The transcription rate would decrease, inhibiting cell functions.
c. The transcription rate decreases due to clogging of the transcription factors.
d. The transcription rate increases due to clogging of the transcription factors.

Eric Goldman

Numerade Educator

Problem 33

3. The $wnt$ transcription pathway is responsible for key changes during animal development. Based on the transcription pathway shown below. In this diagram, arrows indicate the transformation of one substance into another. Square lines, or the lines with no arrowheads, indicate inhibition of the product below the line. Based on this, how would increased $wnt$ gene expression affect the expression of Bar-1?
FIGURE 16.16

Nalvi Duro

Numerade Educator

Problem 34

Describe how RBPs can prevent miRNAs from degrading an RNA molecule.
a. RBPs can bind first to the RNA, thus preventing the binding of miRNA, which degrades RNA.
b. RBPs bind the miRNA, thereby protecting the mRNA from degradation.
c. RBPs methylate miRNA to inhibit its function and thus stop mRNA degradation.
d. RBPs direct miRNA degradation with the help of a DICER protein complex.

Eric Goldman

Numerade Educator

Problem 35

How can external stimuli alter post-transcriptional control of gene expression?
a. UV rays can alter methylation and acetylation of proteins.
b. RNA binding proteins are modified through phosphorylation.
c. External stimuli can cause deacetylation and demethylation of the transcript.
d. UV rays can cause dimerization of the RNA binding proteins.

Prashant Bana

Numerade Educator

Problem 36

Protein modifications can alter gene expression in many ways. Describe how phosphorylation of proteins can alter gene expression.
a. Phosphorylation of proteins can alter translation, RNA shuttling, RNA stability or post transcriptional modification.
b. Phosphorylation of proteins can alter DNA replication, cell division, pathogen recognition
and RNA stability.
c. Phosphorylated proteins affect only translation and can cause cancer by altering the p53
function.
d. Phosphorylated proteins affect only RNA shuttling, RNA stability, and post-translational
modifications.

Eric Goldman

Numerade Educator

Problem 37

Changes in epigenetic modifications alter the accessibility and transcription of DNA. Describe how
environmental stimuli, such as ultraviolet light exposure, could modify gene expression.
a. UV rays could cause methylation and deacetylation of the genes that could alter the accessibility and transcription of DNA.
b. The UV rays could cause phosphorylation and acetylation of the DNA and histones which could alter the transcriptional capabilities of the DNA.
c. UV rays could cause methylation and phosphorylation of the DNA bases which could become dimerized rendering no accessibility of DNA.
d. The UV rays can cause methylation and acetylation of histones making the DNA more tightly packed and leading to inaccessibility.

Nalvi Duro

Numerade Educator

Problem 38

New drugs are being developed that decrease DNA methylation and prevent the removal of acetyl groups from histone proteins. Explain how these drugs could affect gene expression to help kill tumor cells.
a. These drugs maintain the demethylated and the acetylated forms of the DNA to keep transcription of necessary genes “on”.
b. The demethylated and the acetylated forms of the DNA are reversed when the silenced gene is expressed.
c. The drug methylates and acetylates the silenced genes to turn them back “on”.
d. Drugs maintain DNA methylation and acetylation to silence unimportant genes in cancer cells.

Eric Goldman

Numerade Educator

Problem 39

How can understanding the gene expression pattern in a cancer cell tell you something about that specific form of cancer?
a. Understanding gene expression patterns in cancer cells will identify the faulty genes, which is helpful in providing the relevant drug treatment.
b. Understanding gene expression will help diagnose tumor cells for antigen therapy.
c. Gene profiling would identify the target genes of the cancer-causing pathogens.
d. Breast cancer patients who do not express EGFR can respond to anti-EGFR therapy.

Alyssa Mcalarney

Alyssa Mcalarney

Numerade Educator

Problem 40

Explain what personalized medicine is and how it can be used to treat cancer.
a. Personalized medicines would vary based on the type of mutations and the gene’s expression pattern.
b. The medicines are given based on the type of tumor found in the body of an individual.
c. The personalized medicines are provided based only on the symptoms of the patient.
d. The medicines tend to vary depending on the severity and the stage of the cancer.

Eric Goldman

Numerade Educator

Problem 41

Which of the following is found in both prokaryotes and eukaryotes?
a. 3’ poly-A tails
b. 5’ caps
c. promoters
d. introns

Nalvi Duro

Numerade Educator

Problem 42

The enzyme ployadenylate polymerase catalyzes the addition of adenosine monophosphate to the 3’ ends of mRNAs to form a poly-A tail. If the enzyme were blocked so that it could not function, the result would be:
a. increased mRNA stability in eukaryotes, and decreased mRNA stability in prokaryotes
b. decreased mRNA stability in eukaryotes, and no effect in prokaryotes
c. no effect in eukaryotes, and increased mRNA stability in prokaryotes
d. no effect in eukaryotes, and decreased mRNA stability in prokaryotes

Eric Goldman

Numerade Educator

Problem 43

Describe two ways in which gene regulation differs and two ways in which it is similar in prokaryotes and eukaryotes.
a. Prokaryotes show co-transcriptional translation whereas eukaryotes perform transcription prior
to translation; in both cell types, regulation occurs through the binding of transcription factors, activators, and repressors.
b. Prokaryotes perform transcription prior to translation whereas eukaryotes show cotranscriptional translation (the processes occur in the same organelle).
c. Prokaryotes show co-transcriptional translation that is regulated prior to translation whereas eukaryotes perform transcription prior to translation that is regulated only at the level of transcription. In both domains, transcription factors, activators, and repressors provide regulation.
d. Prokaryotes show co-transcriptional translation that occurs in the nucleus whereas eukaryotes
show transcription prior to translation. In both cell types, regulation occurs using transcription factors, activators, and repressors.

Nalvi Duro

Numerade Educator

Problem 44

Lactose digestion in $E$ . coli begins with its hydrolysis by the enzyme $\beta$ -galactosidase. The gene encoding $\beta$ -galactosidase, lacZ, is part of a coordinately regulated operon containing other genes required for lactose utilization. Which of the following figures correctly depicts the interactions at the $lac$ operon when lactose is not being utilized?

Dennis Howard

Numerade Educator

Problem 45

What would be the result of a mutation in the repressor protein that prevented it from binding lactose?
a. The repressor will bind to lactose when it is removed from the operator.
b. The repressor will bind the operator in the presence of lactose.
c. The repressor will not bind the operator in the presence of lactose.
d. The repressor will not bind the operator in the absence of lactose.

Nalvi Duro

Numerade Educator

Problem 46

What type of modification might be observed in the GR gene in all newborn rats?
a. The DNA will have many methyl molecules.
b. The DNA will have many acetyl molecules.
c. The DNA will have few methyl groups.
d. The histones will have many acetyl groups.

Eric Goldman

Numerade Educator

Problem 47

What type of modification will be observed in the GR gene in the highly nurtured rats?
a. The DNA will have many methyl molecules.
b. The DNA will have many acetyl molecules.
c. The DNA will have few methyl groups.
d. The histones will have few acetyl groups.

Alyssa Mcalarney

Alyssa Mcalarney

Numerade Educator

Problem 48

The level of transcription of a gene is tested by creating deletions in the gene as shown in the illustration. These modified genes are tested for their level of transcription: $(++)$ normal transcription levels; $(+)$ low transcription levels; $(+++)$ high transcription levels. Which deletion is in an enhancer involved in regulating the gene?
a. deletion 1
b. deletion 2
c. deletion 3
d. deletion 4

Taylor Jordan

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Problem 49

Which deletion is in a repressor involved in regulating the gene?
a. deletion 1
b. deletion 2
c. deletion 3
d. deletion 4

Nalvi Duro

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Problem 50

The diagram provided shows different regions (1-5) of a pre-mRNA molecule, a mature-mRNA molecule, and the protein corresponding to the mRNA. A mutation in which region is most likely to be damaging to the cell?
a. 1
b. 2
c. 3
d. 5

Eric Goldman

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Problem 51

What do regions 1 and 5 correspond to?
a. exons
b. introns
c. promoters
d. untranslated regions

Marisa A

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Problem 52

What are regions 1 through 5 in the diagram?
a. 1, 3, and 5 are exons; 2 and 4 are introns.
b. 2 and 4 are exons; 1,3, and 5 are introns.
c. 1 and 5 are exons; 2, 3, and 4 are introns.
d. 2, 3, and 4 are exons; 1 and 5 are introns.

Eric Goldman

Numerade Educator

Problem 53

A mutation results in the formation of the mutated maturemRNA as indicated in the diagram. Describe what type of mutation occurred and what the likely outcome of the mutation is.
a. Mutation in the GU-AG sites of introns produced a non-functional protein.
b. A transversion mutation in the introns led to alternative splicing, producing a functional protein.
c. A transversion mutation in the GU-AG site mutated this mRNA, producing a non-functional protein.
d. Transition mutations in the introns could produce a functional protein.

Nalvi Duro

Numerade Educator

Problem 54

The diagram illustrates the role of p53 in response to UV exposure. What would be the result of a mutation in the p53 gene that inactivates it?
a. Skin will peel in response to UV exposure.
b. Apoptosis will occur in response to UV exposure.
c. No DNA damage will occur in response to UV exposure.
d. No peeling of skin will occur in response to UV exposure.

Eric Goldman

Numerade Educator

Problem 55

Which of the following will not occur in response to UV exposure if a p53 mutation inactivates the p53
protein?
1. Damage to DNA
2. p53 activation
3. p21 activation
4. Apoptosis
a. 1, 2, and 3
b. 3 and 4
c. 3
d. 2, 3, and 4

Nalvi Duro

Numerade Educator

Problem 56

What happens when tryptophan is present?
a. The repressor binds to the operator, and RNA synthesis is blocked.
b. RNA polymerase binds to the operator, and RNA synthesis is blocked.
c. Tryptophan binds to the repressor, and RNA synthesis proceeds.
d. Tryptophan binds to RNA polymerase, and RNA synthesis proceeds.

Eric Goldman

Numerade Educator

Problem 57

What happens in the absence of tryptophan?
a. RNA polymerase binds to the repressor
b. the repressor binds to the promoter
c. the repressor dissociates from the operator
d. RNA polymerase dissociates from the promoter

Nalvi Duro

Numerade Educator

Problem 58

Anabaena is a simple multicellular photosynthetic cyanobacterium. In the absence of fixed nitrogen, certain newly developing cells along a filament express genes that code for nitrogen-fixing enzymes and become nonphotosynthetic heterocysts. The specialization is advantageous because some nitrogen-fixing enzymes function best in the absence of oxygen. Heterocysts do not carry out photosynthesis but instead provides adjacent cells with fixed nitrogen and receives fixed carbon and
reduced energy carriers in return. As shown in the diagram above, when there is low fixed nitrogen in the environment, an increase in the concentration of free calcium ions and 2-oxyglutarate stimulates the expression of genes that produce two transcription factors (NtcA and HetR) that promote the expression of genes responsible for heterocyst development. HetR also causes production of a
signal, PatS, that prevents adjacent cells from developing as heterocysts. Based on your understanding of the ways in which signal transmission mediates cell function, which of the following predictions is most consistent with the information given above?
a. In an environment with low fixed nitrogen, treating the Anabaena cells with a calciumbinding compound should prevent heterocyst differentiation.
b. A strain that overexpresses the patS gene should develop many more heterocysts in a low nitrogen environment.
c. In an environment with abundant fixed nitrogen, free calcium levels should be high in all cells,
preventing heterocysts from developing.
d. In environments with abundant fixed nitrogen, loss of the hetR gene should induce heterocyst
development.

Alyssa Mcalarney

Alyssa Mcalarney

Numerade Educator

Problem 59

Which of the following statements about Anabaena is false?
a. Decreasing the concentration of free calcium ions will prevent heterocyst development.
b. In the presence of fixed nitrogen, NtcA will not be expressed.
c. Low fixed nitrogen levels result in increased PatS levels.
d. A mutation in NtcA that makes it nonfunctional will also allow adjacent cells to develop as heterocysts.

Alyssa Mcalarney

Alyssa Mcalarney

Numerade Educator

Problem 60

The operon model describes expression in prokaryotes. Describe this model and the essential difference in the way in which expression is regulated in eukaryotes.

Jonathan Temple

Jonathan Temple

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