20 Questions
What is the advantage of transcription regulators forming heterodimers?
To increase affinity and specificity
What is the characteristic of cooperative binding of transcription regulators to DNA?
Binding is all-or-none, with the cis-regulatory sequence being either fully occupied or empty
What is the nature of DNA binding by transcription regulators?
Dynamic, with molecules in constant motion and rapidly binding and dissociating from DNA
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
How do bacteria regulate the expression of many of their genes?
According to the food sources available in the environment
What triggers the bacterium to utilize alternative sources of carbon?
Absence of glucose
What is the role of the Lac repressor in the Lac operon?
To shut off the operon in the absence of lactose
How do transcription regulators act in eukaryotic gene regulation?
Through Mediator, and also directly with general transcription factors and RNA polymerase
What is the nature of an individual eukaryotic transcription regulator?
A regulatory part that participates in multiple regulatory complexes
How is an eukaryotic gene regulated?
By a committee of proteins that must all be present
What percentage of protein-coding genes are typically devoted to transcription regulators in most organisms?
10%
What is the primary reason why transcription regulators bind to specific cis-regulatory sequences?
To recognize specific DNA sequences
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
What is the result of dimerization of transcription regulators in terms of DNA binding?
Increased affinity and specificity
What is the typical recognition site size for a monomer of a transcription regulator?
4-8 nucleotide pairs
What is the typical arrangement of genes in bacteria?
Genes are arranged in clusters on the chromosome and transcribed from a single promoter
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
How does the tryptophan repressor bind to DNA?
It binds to DNA only when it has bound several molecules of tryptophan
What is the function of the Lac operon?
To import and digest the disaccharide lactose
What is a characteristic feature of eukaryotic gene regulation?
Genes are typically transcribed and regulated individually
Learn about the role of transcription regulators in gene expression, including their recognition of specific cis-regulatory sequences and how they determine the timing and location of gene transcription. Understand the importance of transcription regulators in the cell and their impact on gene expression. Test your knowledge of this fundamental biological process.
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