Regulation of Gene Expression Quiz

What is gene expression?

• The process of converting DNA into RNA

• The process by which information from a gene is used in the synthesis of a functional gene product

• The process of DNA replication

• The process of converting RNA into proteins

Answer explanation

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product, making it the correct choice.

What is the role of the lac repressor in the lac operon?

• Activates transcription of the operon

• Inhibits transcription of the operon

• Cleaves lactose into glucose and galactose

• Transports lactose into the cell

Answer explanation

The lac repressor inhibits transcription of the lac operon by binding to the operator region, preventing RNA polymerase from transcribing the genes involved in lactose metabolism.

What is the function of enhancers in gene regulation?

• Decrease the rate of transcription

• Bind to the operator to block transcription

• Inhibit the binding of RNA polymerase to the promoter

• Increase the likelihood of transcription of a particular gene

Answer explanation

Enhancers increase the likelihood of transcription of a particular gene by interacting with transcription factors and RNA polymerase to enhance gene expression.

What is the process of alternative RNA splicing?

• Conversion of mRNA into tRNA

• Addition of introns to pre-mRNA

• Removal of exons from pre-mRNA

• Shuffling and reconnection of exons in pre-mRNA

Answer explanation

Alternative RNA splicing involves shuffling and reconnection of exons in pre-mRNA to generate different mRNA transcripts.

What is the main function of microRNAs in gene regulation?

• Add methyl groups to DNA

• Transport mRNA from nucleus to cytoplasm

• Cleave and degrade mRNA

• Increase the rate of transcription

Answer explanation

MicroRNAs function by cleaving and degrading mRNA to regulate gene expression.

What is the purpose of post-translational modifications of proteins?

• Remove introns from pre-mRNA

• Transport proteins to the nucleus

• Initiate transcription of genes

• Regulate protein folding and interactions

Answer explanation

Post-translational modifications of proteins regulate protein folding and interactions, ensuring proper structure and function.

Which enzyme is responsible for cleaving preproinsulin to form proinsulin?

• Endoplasmic reticulum

• Methyltransferase-like 3

• DGCR8

• Dicer

Answer explanation

The correct enzyme responsible for cleaving preproinsulin to form proinsulin is the Endoplasmic reticulum.

What is the effect of high levels of tryptophan on the trp operon?

• Increases translation

• Turns on transcription

• Turns off transcription

• Decreases mRNA stability

Answer explanation

High levels of tryptophan act as a corepressor, binding to the trp repressor protein, which then binds to the trp operator, turning off transcription of the trp operon.

What is the function of silencers in gene regulation?

• Increase the rate of transcription

• Decrease the likelihood of transcription of a particular gene

• Promote mRNA degradation

• Bind to enhancers to activate genes

Answer explanation

Silencers function by decreasing the likelihood of transcription of a particular gene, acting as negative regulators of gene expression.

What is the role of catabolite activator protein (CAP) in the lac operon?

• Cleaves lactose into glucose and galactose

• Inhibits transcription

• Transports glucose into the cell

• Activates transcription in the presence of glucose

Answer explanation

The role of catabolite activator protein (CAP) in the lac operon is to activate transcription in the presence of glucose.

Tags

NGSS.HS-LS1-1