Question 1

Early genes of a lytic bacteriophage are transcribed by

Accepted Answer

Early genes of a lytic bacteriophage are transcribed by host RNA polymerase.

Question 2

What is the primary mechanism (or timing)involved in the shutdown of the host gene expression that occurs in bacteria infected by phage T4?

Accepted Answer

The shutdown of host gene expression in bacteria infected by phage T4 occurs after transcription, as the phage modifies the host's transcriptional machinery to prioritize its own gene expression.

Question 3

Which statement about virions is true?

Accepted Answer

Virions are complete virus particles that are produced during the lytic phase of the viral life cycle, where the virus replicates and assembles new virions to be released from the host cell.

Question 4

Which statement about viruses is true?

Accepted Answer

Viruses are not considered living organisms because they lack many basic characteristics of life, including the ability to regulate their internal environment and carry out metabolic processes. They are not composed of cells and can only replicate by hijacking the machinery of living cells.

Answer: C
 Viruses cannot reproduce on their own, and instead require living host cells in order to replicate. Once a virus infects a host cell, it can use the host's cellular machinery to create new virus particles.

Answer: E
 While viruses may be complex in some ways, they are typically much smaller than even the simplest living organisms. They range in size from around 20 nanometers to several hundred nanometers, while most living cells are several micrometers in diameter.

Question 5

Suppose that there is a mutation in the lac operon that prevents the repressor from binding to the operator.In the absence of lactose (or allolactose),the genes of the operon will be _______.In the presence of lactose (or allolactose),the genes will be _______.

Accepted Answer

The answer of Suppose that there is a mutation in...

Question 6

The prokaryotic gene zest5 produces a hypothetical enzyme and is regulated along with other genes that produce other enzymes in the pathway.From the information given,we can conclude that zest5 is a(n)_______ gene.

Accepted Answer

Zest5 is a structural gene because it produces an enzyme and is regulated along with other genes in a pathway, indicating it is part of an operon that codes for enzymes.

Question 7

Viruses

Accepted Answer

Viruses are obligate intracellular parasites, meaning they require a host cell in order to replicate and reproduce. They cannot replicate themselves independently outside of a host cell.

Question 8

In eukaryotic cells,promoters are

Accepted Answer

Promoters are regions of DNA that are not transcribed or translated. Instead, they serve as binding sites for the RNA polymerase and transcription factors, which eventually lead to the initiation of transcription. Once transcription is started, the RNA molecule is transcribed and processed into a mature mRNA that can be translated into a protein. However, the promoter region itself is not transcribed into RNA or translated into protein.

Question 9

Which statement about operons is false?

Accepted Answer

A repressible operon is typically on and is turned off when not needed, not the other way around.

Question 10

Which of the following acts as a corepressor to block transcription of the trp operon?

Accepted Answer

Tryptophan is the corepressor that binds to the trp repressor protein, causing it to bind to the trp operator and prevent transcription of the trp operon.

Question 11

In the absence of substance M,a hypothetical LM operon is turned off.If substance M is abundant,it can bind to the repressor,which permits the polymerase to begin transcribing the DNA.In this case,LM is a(n)_______ operon and M acts as a(n)_______.

Accepted Answer

The LM operon is inducible because it is turned on in the presence of substance M. Substance M acts as an inducer because it binds to the repressor, allowing transcription to occur.

Question 12

What is a likely advantage of transcriptional regulation over allosteric regulation?

Accepted Answer

Transcriptional regulation allows for the complete shut down of enzyme production, whereas allosteric regulation only allows for a decrease in activity. This makes transcriptional regulation more energetically efficient.

Question 13

In eukaryotes,a promoter is the region of

Accepted Answer

In eukaryotes, a promoter is the region of DNA that binds RNA polymerase, which initiates the transcription of a gene into mRNA. Promoters are critical for regulating gene expression, as they determine when and how much of a gene is expressed.

Question 14

Which statement about the early genes in the T4 bacteriophage is false?

Accepted Answer

Early genes in the T4 bacteriophage produce proteins involved in DNA replication, as well as proteins involved in regulating the expression of other viral genes. However, they do not produce the capsid proteins, which are part of the late gene expression program.

Question 15

In a repressible operon,the repressor molecule

Accepted Answer

In a repressible operon, the repressor molecule can control the operon only after it is activated by a corepressor. The corepressor binds to the repressor, changing its conformation so that it can bind to the operator region and block transcription. Without the corepressor, the repressor cannot bind and the operon continues to be transcribed.

Question 16

Suppose that a certain enzyme is synthesized whenever the solution in which the cells are growing contains substance Y.When substance Y is not present,the enzyme is produced only under certain environmental conditions.This phenomenon would most likely be an example of _______ gene regulation.

Accepted Answer

Inducible gene regulation occurs when a gene is turned on in response to the presence of a specific substance or environmental condition. In this scenario, the enzyme is only produced when substance Y is present, indicating that the gene is inducible.

Question 17

Suppose that a certain enzyme is synthesized whenever the solution in which the cells are growing lacks substance X.When substance X is present,the enzyme is produced only under certain environmental conditions.This phenomenon would most likely be an example of _______ gene regulation.

Accepted Answer

The answer of Suppose that a certain enzyme is synthesized...

Question 18

How are inducible and repressible systems similar?

Accepted Answer

Both inducible and repressible systems involve regulatory molecules that bind to the operator to control gene transcription.

Question 19

In what way does gene regulation differ in eukaryotes and prokaryotes?

Accepted Answer

The answer of In what way does gene regulation differ...

Question 20

If a virus is in the lysogenic phase,it will

Accepted Answer

During the lysogenic phase, the virus integrates its DNA into the host cell chromosome. This allows the viral DNA to be replicated along with the host DNA during cell division, without causing viral replication or destruction of the host cell.

Quiz 11: Regulation of Gene Expression

Early genes of a lytic bacteriophage are transcribed by

What is the primary mechanism (or timing) involved in the shutdown of the host gene expression that occurs in bacteria infected by phage T4?

Which statement about virions is true?

Which statement about viruses is true?

Suppose that there is a mutation in the lac operon that prevents the repressor from binding to the operator.In the absence of lactose (or allolactose) ,the genes of the operon will be _.In the presence of lactose (or allolactose) ,the genes will be _.

The prokaryotic gene zest5 produces a hypothetical enzyme and is regulated along with other genes that produce other enzymes in the pathway.From the information given,we can conclude that zest5 is a(n) _______ gene.

Viruses

In eukaryotic cells,promoters are

Which statement about operons is false?

Which of the following acts as a corepressor to block transcription of the trp operon?

In the absence of substance M,a hypothetical LM operon is turned off.If substance M is abundant,it can bind to the repressor,which permits the polymerase to begin transcribing the DNA.In this case,LM is a(n) _ operon and M acts as a(n) _.

What is a likely advantage of transcriptional regulation over allosteric regulation?

In eukaryotes,a promoter is the region of

Which statement about the early genes in the T4 bacteriophage is false?

In a repressible operon,the repressor molecule

Suppose that a certain enzyme is synthesized whenever the solution in which the cells are growing contains substance Y.When substance Y is not present,the enzyme is produced only under certain environmental conditions.This phenomenon would most likely be an example of _______ gene regulation.

Suppose that a certain enzyme is synthesized whenever the solution in which the cells are growing lacks substance X.When substance X is present,the enzyme is produced only under certain environmental conditions.This phenomenon would most likely be an example of _______ gene regulation.

How are inducible and repressible systems similar?

In what way does gene regulation differ in eukaryotes and prokaryotes?

If a virus is in the lysogenic phase,it will

Quiz 11: Regulation of Gene Expression

Early genes of a lytic bacteriophage are transcribed by

What is the primary mechanism (or timing) involved in the shutdown of the host gene expression that occurs in bacteria infected by phage T4?

Which statement about virions is true?

Which statement about viruses is true?

Suppose that there is a mutation in the lac operon that prevents the repressor from binding to the operator.In the absence of lactose (or allolactose) ,the genes of the operon will be _______.In the presence of lactose (or allolactose) ,the genes will be _______.

The prokaryotic gene zest5 produces a hypothetical enzyme and is regulated along with other genes that produce other enzymes in the pathway.From the information given,we can conclude that zest5 is a(n) _______ gene.

Viruses

In eukaryotic cells,promoters are

Which statement about operons is false?

Which of the following acts as a corepressor to block transcription of the trp operon?

In the absence of substance M,a hypothetical LM operon is turned off.If substance M is abundant,it can bind to the repressor,which permits the polymerase to begin transcribing the DNA.In this case,LM is a(n) _______ operon and M acts as a(n) _______.

What is a likely advantage of transcriptional regulation over allosteric regulation?

In eukaryotes,a promoter is the region of

Which statement about the early genes in the T4 bacteriophage is false?

In a repressible operon,the repressor molecule

Suppose that a certain enzyme is synthesized whenever the solution in which the cells are growing contains substance Y.When substance Y is not present,the enzyme is produced only under certain environmental conditions.This phenomenon would most likely be an example of _______ gene regulation.

Suppose that a certain enzyme is synthesized whenever the solution in which the cells are growing lacks substance X.When substance X is present,the enzyme is produced only under certain environmental conditions.This phenomenon would most likely be an example of _______ gene regulation.

How are inducible and repressible systems similar?

In what way does gene regulation differ in eukaryotes and prokaryotes?

If a virus is in the lysogenic phase,it will

Suppose that there is a mutation in the lac operon that prevents the repressor from binding to the operator.In the absence of lactose (or allolactose) ,the genes of the operon will be _.In the presence of lactose (or allolactose) ,the genes will be _.

In the absence of substance M,a hypothetical LM operon is turned off.If substance M is abundant,it can bind to the repressor,which permits the polymerase to begin transcribing the DNA.In this case,LM is a(n) _ operon and M acts as a(n) _.