Question 1

Lysis of the host cell is caused by

Accepted Answer

A)   the cell's bursting due to the large number of viral particles.
B)   the cell's opening up in an attempt to release the viruses.
C)   an attack on the cell wall by a product of the viral gene.
D)   an as yet unknown mechanism.
E)   None of the above

Question 2

Suppose that a cell has a mutation that deletes the gene encoding the operator for a certain operon, and a plasmid is introduced into the host cell that carries a wild-type copy of the operator. Is normal regulation of this operon restored in the presence of this plasmid?

Accepted Answer

No. The operator site on the plasmid can...

Question 3

When E. coli are grown in a medium with low levels of lactose,

Accepted Answer

A)   all the enzymes of the lactose operon are present in very small quantities.
B)   all the enzymes of the lactose operon are present in large quantities.
C)   no enzymes of the lactose operon are present.
D)    β\betaβ -galactosidase and permease are present in small quantities, but transacetylase is present in large quantities.
E)   the mRNA of the lactose operon is not present at all.

Question 4

Transcription of eukaryotic genes requires

Accepted Answer

A)   binding of RNA polymerase to the promoter.
B)   binding of several transcription factors.
C)   capping of mRNA.
D)   Both a and b
E)   All of the above

Question 5

Animal viruses that integrate their DNA into the host chromosome

Accepted Answer

A)   have DNA as their genome.
B)   are prophages.
C)   copy their RNA genome into DNA using reverse transcriptase.
D)   replicate their genome using RNA polymerase.
E)   can undergo only a lytic infection cycle. C

Question 6

A herpes virus causes both chicken pox and shingles in humans. People who have had chicken pox may be afflicted with shingles much later in life. What is a likely explanation for this?

Accepted Answer

A)   The intact virus was harbored within cells and was activated.
B)   The viral DNA had been incorporated into the host's genome and was induced to enter the lytic cycle.
C)   The viral DNA became active while integrated into the host's DNA.
D)   Expression of host DNA genes was shut down.
E)   All of the above B

Question 7

CREB is a transcription factor that regulates gene expression. It binds to DNA and activates promoters of genes involved in addictive behaviors in alcoholism. Researchers compared CREB levels in the brains of a strain of rats called P rats and wild-type rats. When P rats consumed alcohol,

Accepted Answer

A)   the total levels of CREB increased.
B)   the total levels of CREB decreased.
C)   the total levels of CREB remained the same.
D)   levels of phosphorylated CREB increased.
E)   levels of phosphorylated CREB decreased.

Question 8

The most efficient means of regulating protein synthesis is by

Accepted Answer

A)   selective blocking of transcription.
B)   translation of the mRNA.
C)   inhibition of the protein.
D)   degradation of the protein.
E)   transcription of the gene.

Question 9

What effect does the presence of ample glucose have on the amount of lac operon transcription?

Accepted Answer

A)   It increases the cAMP concentration, which in turn causes a decreased rate of transcription.
B)   It decreases the cAMP concentration, which in turn causes an increased rate of transcription.
C)   It increases the rate of transcription.
D)   It decreases the rate of transcription.
E)   None of the above

Question 10

In eukaryotic cells, a positive regulator or enhancer

Accepted Answer

A)   binds to the enhancer region to block transcription.
B)   is made of RNA.
C)   binds to an activator protein to increase transcription rates.
D)   is a carbohydrate.
E)   is an enzyme.

Question 11

It is found that a certain enzyme is synthesized whenever the solution in which the cells are growing lacks substance X. This phenomenon is most likely an example of _______ gene regulation.

Accepted Answer

A)   inducible
B)   positive
C)   negative
D)   repressible
E)   positive-negative

Question 12

The TATA box is a(n)

Accepted Answer

A)   sequence close to the promoter region of many genes.
B)   square-shaped sequence.
C)   enhancer consensus sequence.
D)   activator sequence necessary for proper translation.
E)   None of the above

Question 13

_______ syndrome is due to genomic imprinting. If the male region on chromosome 15 is deleted, the baby develops a phenotype marked by muscle weakness and obesity.

Accepted Answer

Prader-Willi

Question 14

The influenza virus and the HIV virus differ in that only the influenza virus can

Accepted Answer

A)   produce and use reverse transcriptase.
B)   use RNA as its genetic material.
C)   use RNA as genetic information and mRNA without generating a DNA molecule.
D)   infect both horses and humans.
E)   All of the above

Question 15

A cell that contains three Barr bodies will necessarily have

Accepted Answer

A)   three Y chromosomes.
B)   three X chromosomes.
C)   four Y chromosomes.
D)   four X chromosomes.
E)   three nucleoli.

Question 16

What would happen initially to cells that lack a functional ubiquitin?

Accepted Answer

A)   Nothing would happen.
B)   Transcriptional initiation would increase.
C)   Protein degradation would decrease.
D)   Histone modifications would increase.
E)   Translation of proteins would be more efficient.

Question 17

Common structural motifs for transcription factors with specific DNA binding domains do not include

Accepted Answer

A)   helix-loop-helix.
B)   helix-turn-helix.
C)   zinc finger.
D)    β\betaβ -pleated sheet.
E)   leucine zipper.

Question 18

If the gene encoding the trp repressor is mutated such that it can no longer bind tryptophan but can still bind the operon, will transcription of the trp operon occur?

Accepted Answer

A)   Yes, because the trp repressor can bind the trp operon and block transcription only when it is bound to tryptophan.
B)   No, because this mutation does not affect the part of the repressor that can bind the operator.
C)   No, because the trp operon is repressed only when tryptophan levels are high.
D)   Yes, because the trp operon can allosterically regulate the enzymes needed to synthesize the amino acid tryptophan.
E)   No, because the repressor will be continuously bound to the operator.

Question 19

The drought stress response in plants is an example of

Accepted Answer

A)   a transcription factor.
B)   coordinated gene expression.
C)   a way to increase water intake.
D)   Both a and b
E)   None of the above

Question 20

A positive control process that relies on increasing the affinity of promoters for RNA polymerase is called _______.

Accepted Answer

catabolic ...

Exam 16: Regulation of Gene Expression

Lysis of the host cell is caused by

Correct AnswerverifiedShow Answer

Suppose that a cell has a mutation that deletes the gene encoding the operator for a certain operon, and a plasmid is introduced into the host cell that carries a wild-type copy of the operator. Is normal regulation of this operon restored in the presence of this plasmid?

Correct AnswerverifiedNo. The operator site on the plasmid can...View AnswerShow Answer

When E. coli are grown in a medium with low levels of lactose,

Correct AnswerverifiedShow Answer

Transcription of eukaryotic genes requires

Correct AnswerverifiedShow Answer

Animal viruses that integrate their DNA into the host chromosome

Correct AnswerverifiedC

A herpes virus causes both chicken pox and shingles in humans. People who have had chicken pox may be afflicted with shingles much later in life. What is a likely explanation for this?

Correct AnswerverifiedB

CREB is a transcription factor that regulates gene expression. It binds to DNA and activates promoters of genes involved in addictive behaviors in alcoholism. Researchers compared CREB levels in the brains of a strain of rats called P rats and wild-type rats. When P rats consumed alcohol,

Correct AnswerverifiedShow Answer

The most efficient means of regulating protein synthesis is by

Correct AnswerverifiedShow Answer

What effect does the presence of ample glucose have on the amount of lac operon transcription?

Correct AnswerverifiedShow Answer

In eukaryotic cells, a positive regulator or enhancer

Correct AnswerverifiedShow Answer

It is found that a certain enzyme is synthesized whenever the solution in which the cells are growing lacks substance X. This phenomenon is most likely an example of _______ gene regulation.

Correct AnswerverifiedShow Answer

The TATA box is a(n)

Correct AnswerverifiedShow Answer

_______ syndrome is due to genomic imprinting. If the male region on chromosome 15 is deleted, the baby develops a phenotype marked by muscle weakness and obesity.

Correct AnswerverifiedPrader-Willi

The influenza virus and the HIV virus differ in that only the influenza virus can

Correct AnswerverifiedShow Answer

A cell that contains three Barr bodies will necessarily have

Correct AnswerverifiedShow Answer

What would happen initially to cells that lack a functional ubiquitin?

Correct AnswerverifiedShow Answer

Common structural motifs for transcription factors with specific DNA binding domains do not include

Correct AnswerverifiedShow Answer

If the gene encoding the trp repressor is mutated such that it can no longer bind tryptophan but can still bind the operon, will transcription of the trp operon occur?

Correct AnswerverifiedShow Answer

The drought stress response in plants is an example of

Correct AnswerverifiedShow Answer

A positive control process that relies on increasing the affinity of promoters for RNA polymerase is called _______.

Correct Answerverifiedcatabolic ...View AnswerShow Answer

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No. The operator site on the plasmid can...
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C

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B

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Prader-Willi

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catabolic ...
View Answer