Gene Expression and Regulatory Proteins in Eukaryotic Cells

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Questions and Answers

What can eukaryotic activator proteins do to stimulate transcription initiation?

Prevent RNA polymerase II recruitment

Alter local features in chromatin structure (correct)

Inhibit DNA binding proteins

Promote DNA methylation

How can a single gene regulatory protein in eukaryotic cells affect gene expression?

Directly inhibit all gene transcription

Increase the synthesis of another gene regulatory protein

Coordinate the expression of several different genes (correct)

Prevent gene transcription initiation

Which type of DNA-binding proteins bind to the surface of DNA without opening the DNA double-helix?

Helicases

Ligases

Transcription factors (correct)

Topoisomerases

What is the role of general transcription factor TFIID in eukaryotic gene regulation?

Recruitment of RNA polymerase II to the promoter Signup and view all the answers

In eukaryotes, what separates active and inactive chromatin?

Histone acetylation Signup and view all the answers

How do eukaryotic gene repressor proteins act to inhibit gene expression?

Bind general transcription factor TFIID Signup and view all the answers

In prokaryotic gene expression, what is responsible for initiating transcription?

RNA polymerase Signup and view all the answers

What event leads to the opening of chromatin for transcription initiation in specific genes?

Remodeling the chromatin and modifying histones Signup and view all the answers

Which process involves proteins being separated by charge in the first dimension and by molecular weight in the second dimension?

Protein 2-dimensional gel-electrophoresis Signup and view all the answers

What type of gene expression control involves the binding of DNA-binding proteins like transcription factors?

Transcriptional synergy Signup and view all the answers

What is the role of the repressor protein in gene expression?

Binds to DNA and prevents transcription. Signup and view all the answers

In the Lac operon, which molecule regulates the operon by interacting with the Catabolite Activating Protein (CAP)?

Glucose Signup and view all the answers

What is the function of the mediator protein complex in eukaryotic gene control regions?

Establishes interactions between components. Signup and view all the answers

Which sequence on DNA binds to the general transcription factor TFIID in eukaryotes?

TATA sequence Signup and view all the answers

How can gene activation at a distance be facilitated in eukaryotes?

By binding of an activator protein to DNA. Signup and view all the answers

Which method is used to determine whether a protein associates with DNA at a specific location on the chromosome?

Chromatin immunoprecipitation Signup and view all the answers

In prokaryotic gene expression, what is the role of polycistronic messenger RNAs?

They encode multiple proteins on a single mRNA molecule. Signup and view all the answers

Which type of gene regulation involves the separation of active and inactive chromatin regions?

Chromatin structure regulation Signup and view all the answers

What is the main function of transcription factors in eukaryotic gene expression?

Activate or repress transcription Signup and view all the answers

How are DNA fragments amplified for analysis after chromatin immunoprecipitation?

Polymerase chain reaction (PCR) Signup and view all the answers

What is the significance of different cell types containing the same DNA but expressing different proteins?

It explains the presence of different cell functions in multicellular organisms. Signup and view all the answers

In prokaryotic cells, how are genes turned on/off?

Via binding of regulatory proteins to the operator region Signup and view all the answers

What does transcriptional synergy refer to?

The simultaneous activation of multiple genes by a single transcription factor Signup and view all the answers

How can the activity of gene regulatory proteins in eukaryotic cells be altered?

By changing the DNA sequence they bind to Signup and view all the answers

What is one way proteins assemble at the promoter site to activate transcription in eukaryotic cells?

By interacting with DNA-binding proteins Signup and view all the answers

Study Notes

Eukaryotic Transcription Regulation

Eukaryotic activator proteins stimulate transcription initiation by binding to specific DNA sequences and recruiting general transcription machinery.
A single gene regulatory protein can enhance or repress gene expression by interacting with other proteins or DNA elements, affecting transcription levels.

DNA-Binding Proteins

Some DNA-binding proteins contact the DNA double-helix surface without unwinding it; these proteins can influence transcription regulation while maintaining DNA structure.
General transcription factor TFIID recognizes and binds to the TATA box in the promoter region, playing a crucial role in assembling the transcription complex.

Chromatin Structure

Active chromatin is usually less condensed and associated with specific histone modifications compared to inactive chromatin, which is more tightly packed and often includes repressive marks.
Eukaryotic gene repressor proteins inhibit gene expression by recruiting co-repressors that modify chromatin structure or interfere with transcription factor binding.

Prokaryotic vs. Eukaryotic Transcription

In prokaryotes, transcription initiation is triggered by RNA polymerase binding to promoter regions, often regulated by sigma factors.
The opening of chromatin for transcription initiation at specific genes typically involves histone modifications and the action of chromatin-remodeling complexes.

Protein Analysis Techniques

Two-dimensional gel electrophoresis separates proteins based on charge in the first dimension and molecular weight in the second dimension, allowing for visual analysis of protein profiles.
Techniques like ChIP (chromatin immunoprecipitation) allow for determination of protein-DNA interactions at specific chromosomal locations.

Gene Expression Control

Gene expression control is influenced by DNA-binding proteins, including transcription factors that can activate or repress transcription based on the cellular context.
In the Lac operon, glucose levels regulate the operon by influencing the binding of the Catabolite Activating Protein (CAP) to its site, which in turn affects the activity of RNA polymerase.

Mediator Complex and Transcription Factors

The mediator protein complex serves as a bridge between activators/repressors and the transcription machinery, facilitating gene transcription.
Transcription factors play a central role in eukaryotic gene expression by modulating the interaction between RNA polymerase and the gene's promoter.

Genetic Variation and Expression

Different cell types express distinct proteins despite containing the same DNA, resulting in varied functions and characteristics based on gene regulation mechanisms.
In prokaryotic cells, operons can be turned on/off through regulatory proteins responding to environmental signals, allowing efficient resource use.

Additional Concepts

Transcriptional synergy refers to the cooperative interaction between multiple transcription factors to enhance the transcription of target genes.
The activity of gene regulatory proteins can be altered through post-translational modifications, changing their ability to interact with DNA or other proteins.
Proteins can assemble at the promoter site in eukaryotic cells through a combination of transcription factor binding and mediator complex recruitment, leading to transcriptional activation.

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Description

Explore the alteration of gene regulatory proteins in eukaryotic cells and how phosphorylation plays a role. Learn about how a single gene regulatory protein can coordinate the expression of several different genes. This quiz covers topics such as DNA binding proteins, transcription factors, prokaryotic and eukaryotic gene expression, and chromatin structure activation.