Transcription Regulators in Gene Expression

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What is the advantage of transcription regulators forming heterodimers?

To decrease affinity and specificity

To increase affinity and specificity (correct)

To bind to RNA instead of DNA

To reduce the dynamic nature of DNA binding

What is the characteristic of cooperative binding of transcription regulators to DNA?

Binding is only possible at low protein concentrations

Binding is gradual and dependent on protein concentration

Binding is all-or-none, with the cis-regulatory sequence being either fully occupied or empty (correct)

Binding is only possible at high protein concentrations

What is the nature of DNA binding by transcription regulators?

Only possible at specific DNA sequences

Dynamic, with molecules in constant motion and rapidly binding and dissociating from DNA (correct)

Static, with molecules binding permanently to DNA

Only possible in the presence of other proteins

What is the significance of a transcription regulator being fully bound to its cis-regulatory sequence?

It is an average of many individual association and dissociation events over time Signup and view all the answers

How do bacteria regulate the expression of many of their genes?

According to the food sources available in the environment Signup and view all the answers

What triggers the bacterium to utilize alternative sources of carbon?

Absence of glucose Signup and view all the answers

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

To shut off the operon in the absence of lactose Signup and view all the answers

How do transcription regulators act in eukaryotic gene regulation?

Through Mediator, and also directly with general transcription factors and RNA polymerase Signup and view all the answers

What is the nature of an individual eukaryotic transcription regulator?

A regulatory part that participates in multiple regulatory complexes Signup and view all the answers

How is an eukaryotic gene regulated?

By a committee of proteins that must all be present Signup and view all the answers

What percentage of protein-coding genes are typically devoted to transcription regulators in most organisms?

10% Signup and view all the answers

What is the primary reason why transcription regulators bind to specific cis-regulatory sequences?

To recognize specific DNA sequences Signup and view all the answers

Why do transcription regulators typically make the majority of their contacts with the major groove of DNA?

Because it is wider and displays more molecular features Signup and view all the answers

What is the result of dimerization of transcription regulators in terms of DNA binding?

Increased affinity and specificity Signup and view all the answers

What is the typical recognition site size for a monomer of a transcription regulator?

4-8 nucleotide pairs Signup and view all the answers

What is the typical arrangement of genes in bacteria?

Genes are arranged in clusters on the chromosome and transcribed from a single promoter Signup and view all the answers

What is the role of the tryptophan repressor in regulating the tryptophan operon?

It binds to the operator and blocks access of RNA polymerase to the promoter Signup and view all the answers

How does the tryptophan repressor bind to DNA?

It binds to DNA only when it has bound several molecules of tryptophan Signup and view all the answers

What is the function of the Lac operon?

To import and digest the disaccharide lactose Signup and view all the answers

What is a characteristic feature of eukaryotic gene regulation?

Genes are typically transcribed and regulated individually Signup and view all the answers