Operon and Gene Regulation Quiz

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What is the role of the cAMP receptor protein in the positive transcriptional control system?

The cAMP receptor protein is a regulatory gene product that codes for the expressor protein. (correct)
The cAMP receptor protein binds to the gene repressor to inhibit transcription.
The cAMP receptor protein binds to the operator locus to enable gene function.
The cAMP receptor protein is a co-repressor that binds to the RNAP to prevent promoter attachment.

What is the role of a co-repressor in the negative transcriptional control system?

The co-repressor binds to the gene expressor to activate transcription.
The co-repressor binds to the RNAP to prevent promoter attachment.
The co-repressor binds to the gene repressor to inhibit its binding to the operator locus. (correct)
The co-repressor is a regulatory gene product that codes for the expressor protein.

How does the RNAP and promoter attachment process work in the positive transcriptional control system?

The co-repressor protein binds to the RNAP to block its attachment to the promoter.
The cAMP receptor protein binds to the RNAP to prevent its attachment to the promoter.
The gene expressor protein binds to the RNAP to facilitate its attachment to the promoter. (correct)
The RNAP binds directly to the promoter to initiate transcription.

What is the role of the trp regulatory gene in the negative repressible system?

The trp regulatory gene codes for the gene repressor protein that binds to the operator locus to prevent transcription. (A) Signup and view all the answers

How does the negative repressible system control gene expression?

The gene repressor protein is only produced when the substrate is present, and it binds to the operator locus to prevent transcription. (D) Signup and view all the answers

What is the role of the operator locus in the negative inducible system?

The operator locus enables the gene repressor protein to bind to it and prevent transcription. (B) Signup and view all the answers

What is the function of cAMP receptor protein (CRP) in the regulation of gene expression?

Facilitates attachment of RNA polymerase to the promoter (A) Signup and view all the answers

In the tryptophan operon, what role does the trp regulatory gene (trp R) play?

Codes for a repressor protein sensitive to tryptophan levels (A) Signup and view all the answers

What is the purpose of a co-repressor in a negative repressible system?

Inhibits gene expression when bound to a repressor (D) Signup and view all the answers

How does RNAP affect gene transcription in prokaryotes?

Binds to the promoter with the help of cAMP receptor protein (D) Signup and view all the answers

What happens when a suitable inducer (like allolactose) is present in an operon?

Removes the repressor from the operator to allow transcription (C) Signup and view all the answers

Where does the CRP (cAMP receptor protein) bind to regulate gene expression in prokaryotes?

Promoter region (D) Signup and view all the answers

What is the role of cAMP in the regulation of gene expression?

cAMP is a positive regulator that enhances the binding of RNAP to the promoter (D) Signup and view all the answers

Which of the following best describes the role of CRP in the regulation of gene expression?

CRP is a positive regulator that enhances the binding of RNAP to the promoter (D) Signup and view all the answers

What is the relationship between the presence of a co-repressor and the binding of the repressor protein to the control sequence?

The presence of the co-repressor causes the repressor protein to bind to the control sequence, turning the gene off (B) Signup and view all the answers

What is the primary difference between an inducible operon and a repressible operon?

An inducible operon is turned on by the presence of an inducer, while a repressible operon is turned on by the absence of a co-repressor (C) Signup and view all the answers

How does a mutation in the trp regulatory gene affect the expression of the trp operon?

A mutation in the trp regulatory gene would cause the trp operon to be permanently turned off (A) Signup and view all the answers

What is the primary function of the capsid in a virus particle?

The capsid protects the viral genomic material from the host cell's defenses (A) Signup and view all the answers

What is the primary difference between a lytic cycle and a lysogenic cycle in viral replication?

In a lytic cycle, the virus causes the host cell to lyse and release new viral particles, while in a lysogenic cycle, the virus remains dormant within the host cell (D) Signup and view all the answers

Which of the following is a common feature of both beneficial and harmful mutations?

Beneficial and harmful mutations can both be caused by changes in the DNA sequence, including point mutations, reading frameshifts, and chromosome/block mutations (A) Signup and view all the answers

What is the primary difference between a gametic mutation and a somatic mutation?

Gametic mutations can be passed on to future generations, while somatic mutations cannot (C) Signup and view all the answers

cAMP Receptor Protein (CRP)

A regulatory protein that enhances transcription by facilitating RNA polymerase attachment to the promoter.

Co-repressor

A substance that inhibits gene expression by binding to a repressor, enhancing its ability to bind to DNA.

Positive Transcriptional Control

A mechanism where an expressor protein aids RNA polymerase in binding to the promoter for gene activation.

Tryptophan Regulatory Gene

The gene coding for the repressor protein that prevents transcription in the presence of tryptophan.