Gene Regulation and Transcription

Which of the following is NOT a way in which gene regulation occurs at the level of transcription?

Introns

What is the sequence of DNA to which RNA polymerase binds to start transcription called?

Promoter

In prokaryotes, what type of proteins bind to specific sites on DNA to activate transcription?

Activators

What is the name of the protein that activates transcription of the lac operon in E. coli?

CAP

Which of the following statements about enhancers is true?

Enhancers interact with activator proteins

What do repressors do in gene regulation?

Impede RNA polymerase progress on the DNA

What sets eukaryotes apart from prokaryotes in terms of transcriptional regulation?

Eukaryotes have more sophisticated responses to environmental conditions

Which term is used to describe when a cell is actively using certain genes?

Expression

What is the general idea behind DNA regulation in organisms?

Different types of cells transcribe and translate genes at different times

In multicellular organisms, why do cells with the same DNA have different roles?

They produce different proteins and enzymes

What is the term for a group of genes associated with one promoter in prokaryotes?

Operon

How do repressors affect transcription?

Block it

What is the function of an activator in DNA regulation?

Enhance transcription

How do co-repressors influence gene transcription?

Decrease it

Which term describes small molecules that can activate an activator in gene regulation?

Inducers

What is the lac operon primarily involved in?

Metabolism of lactose

What is the role of allolactose in the lac operon?

It binds to the Lac repressor

In the absence of lactose, what is the state of the lac repressor protein?

Bound to the operator

In both eukaryotes and prokaryotes, gene expression is primarily regulated at the level of?

Transcription

When both glucose and lactose are present, what happens to transcription in the lac operon?

Decreases slightly

What is the function of cyclic AMP in the lac operon regulation?

Enhances transcription

How does high glucose concentration affect cyclic AMP production?

Decreases it

Altering patterns of gene expression in prokaryotes would most likely serve the organism's survival in which of the following ways?

Allowing the organism to adjust to changes in environmental conditions

Which of the following statements best explains how the genes for antibiotic resistance can be transmitted between bacteria without the exchange of bacterial chromosomal DNA?

The genes for antibiotic resistance are located on a plasmid that can be passed on to neighboring bacteria

What does the operon model attempt to explain?

The coordinated control of gene expression in bacteria.

What is a repressible operon?

An operon that is normally turned on but can be inhibited by the presence of a specific molecule.

How does a mutation in the promoter region affect gene expression?

It can influence the binding of RNA polymerase to the DNA, potentially affecting transcription.

When is the lactose operon likely to be transcribed?

When cyclic AMP and lactose levels are both high within the cell.

How does active CAP induce expression of the lactose operon?

It stimulates the binding of RNA polymerase to the promoter.

What must occur for a repressible operon to be transcribed?

RNA polymerase must bind to the promoter, and the repressor must be inactive.

What happens when allolactose enters an E. coli cell?

Allolactose binds to the repressor protein, preventing it from inhibiting transcription.

How does altering patterns of gene expression benefit prokaryotes?

It allows the organism to adjust to changes in environmental conditions.

What causes muscle cells and nerve cells to differ in structure?

They have different genes expressed.

What is the effect of methylated DNA on transcription?

It typically slows down or turns off the process of transcription.

What are genomic imprinting, DNA methylation, and histone acetylation examples of?

Epigenetic phenomena.

What proportion of the human genome codes for proteins or functional RNA?

Approximately 1.5%.

At what level is gene expression primarily regulated in both eukaryotes and prokaryotes?

At the level of transcription.

What can inhibit transcription by blocking the binding of transcription factors?

A repressor.

What component increases transcription by helping RNA polymerase bind to DNA?

CAP binding site.

How are epigenetic modifications best described?

Reversible chemical changes that affect gene expression.

What is chromatin?

A DNA-protein complex that can be condensed or relaxed.

What mechanism can directly prevent transcription factor binding to DNA?

DNA methylation.

Which structure is part of an operon?

Operator.

What is the role of miRNA?

It binds mRNA to block translation or degrade it.

How do enhancers function?

They increase transcription by binding activator proteins.

What is the primary outcome of chromatin being in a highly condensed state?

Reduced accessibility for transcription.