Gene Regulation and Transcription Factors
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Questions and Answers

What is a primary function of cis-regulatory elements (CREs)?

  • To regulate the transcription of neighboring genes (correct)
  • To serve as templates for protein synthesis
  • To facilitate DNA replication
  • To code for amino acids directly

Which of the following accurately describes why CREs are referred to as 'cis' elements?

  • They are always found in introns
  • They are located on the same DNA strand as the genes they regulate (correct)
  • They exist in the cytoplasm
  • They bind to genes on different chromosomes

What role do transcription factors play in the function of CREs?

  • They modify the DNA sequence
  • They bind to CREs and regulate gene expression (correct)
  • They replicate the DNA strands
  • They directly code for proteins

Which type of CRE would most likely inhibit gene transcription?

<p>Silencer (A)</p> Signup and view all the answers

How do CREs achieve their regulatory function?

<p>By integrating regulatory signals at specific times and places (A)</p> Signup and view all the answers

Which statement best describes the role of mRNA in gene regulation?

<p>Different types of mRNA indicate distinct cellular functions. (D)</p> Signup and view all the answers

What is the primary control point for gene expression?

<p>Initiation of transcription. (D)</p> Signup and view all the answers

What advantage does RNA transcription provide in gene regulation?

<p>Multiple proteins can be synthesized from one mRNA molecule. (D)</p> Signup and view all the answers

What happens during the elongation phase of transcription?

<p>RNA polymerase synthesizes mRNA along the DNA. (B)</p> Signup and view all the answers

Which statement is least accurate regarding the stages of transcription?

<p>Initiation involves the synthesis of mRNA. (A)</p> Signup and view all the answers

Which component is specifically involved in binding to the TATA box within the promoter region?

<p>TBP and associated factors (A)</p> Signup and view all the answers

What precisely is indicated by the curved arrow moving towards the gene in the diagram?

<p>The function of RNA Pol II (B)</p> Signup and view all the answers

Which of the following statements is true regarding the promoter region?

<p>It comprises the TF site, TATA box, and core promoter elements. (D)</p> Signup and view all the answers

What is the implication of the phrase 'but what about far away?' in the context of gene regulation?

<p>It highlights the role of distant regulatory elements in gene expression. (A)</p> Signup and view all the answers

Which of the following components of gene regulation is located closest to the target gene?

<p>Core part of transcription (D)</p> Signup and view all the answers

What role does gene regulation play in cellular functions?

<p>It determines which genes are expressed and how much. (A)</p> Signup and view all the answers

What would happen if the gene expression switch is in the OFF position?

<p>There is no gene expression or protein synthesis. (A)</p> Signup and view all the answers

How does gene expression affect cell types despite having the same genome?

<p>It allows for different genes to be expressed in various cells. (B)</p> Signup and view all the answers

What mechanism is primarily illustrated by the ON/OFF switch in gene expression?

<p>Transcriptional activation or repression. (A)</p> Signup and view all the answers

Why is it crucial for gene regulation to occur at the right times and extents?

<p>To maintain cellular homeostasis and proper function. (B)</p> Signup and view all the answers

What is the primary role of enhancers and silencers in gene transcription?

<p>To act as attachment sites for activator and repressor proteins (C)</p> Signup and view all the answers

How far can distance-independent cis-regulatory elements (CREs) be located from the transcription initiation site?

<p>They can be located thousands of base pairs away (C)</p> Signup and view all the answers

What effect do activators have when binding to enhancers?

<p>They increase basal levels of transcription (C)</p> Signup and view all the answers

What is a characteristic feature of distance-independent CREs concerning their binding ability?

<p>Their binding can be reversed (A)</p> Signup and view all the answers

Which statement best describes the role of repressor proteins when bound to silencers?

<p>They block the binding of activators (C)</p> Signup and view all the answers

Which of the following best describes constitutive genes?

<p>Genes that are expressed all the time and produce essential proteins (B)</p> Signup and view all the answers

Which of the following is an example of a product of constitutive genes?

<p>Enzymes that catalyse glycolysis (A)</p> Signup and view all the answers

Which component of the core promoter is primarily responsible for the binding of basal factors?

<p>TATA box (A)</p> Signup and view all the answers

What is the approximate distance in base pairs from the promoter-proximal elements to the transcription start site?

<p>200 bp (D)</p> Signup and view all the answers

Which statement accurately reflects the role of constitutive genes in the cell?

<p>They produce RNA polymerase and other critical components for cell function. (D)</p> Signup and view all the answers

What role do transcription factors play in relation to the core promoter once the TATA binding protein binds?

<p>They facilitate the binding of additional regulatory proteins. (C)</p> Signup and view all the answers

What is another term often used to describe constitutive genes?

<p>Housekeeping genes (D)</p> Signup and view all the answers

Which of the following sequences represents the TATA box in eukaryotic transcription?

<p>5'–TATAAA–3' (B)</p> Signup and view all the answers

Which proteins associated with constitutive genes play a structural role in cells?

<p>Proteins such as actin and tubulin (B)</p> Signup and view all the answers

Which element is located closest to the mRNA produced from transcription initiation?

<p>Transcription start site (D)</p> Signup and view all the answers

What is the primary reason liver cells express the alcohol dehydrogenase gene?

<p>To remove alcohol from the bloodstream. (A)</p> Signup and view all the answers

Which statement accurately describes gene expression in neurons compared to liver cells?

<p>Neurons do not express genes associated with toxin removal. (C)</p> Signup and view all the answers

How do liver cells regulate their use of neurotransmitter genes?

<p>By keeping them permanently off. (A)</p> Signup and view all the answers

What do the diagrams in the document illustrate concerning liver cells and neurons?

<p>The differences in gene expression between the two cell types. (A)</p> Signup and view all the answers

Which of the following functions is NOT performed by liver cells according to the document?

<p>Generating signaling neurotransmitters. (B)</p> Signup and view all the answers

What is the primary role of promoter proximal elements in gene transcription?

<p>To facilitate high levels of transcription and gene expression. (B)</p> Signup and view all the answers

How do constitutive genes differ from genes expressed only in specific cell types?

<p>Constitutive genes have common promoter proximal elements used in all cells. (C)</p> Signup and view all the answers

Which statement is true regarding the role of activators in relation to promoter proximal elements?

<p>Activators are recognized by specific promoter proximal elements to regulate transcription levels. (C)</p> Signup and view all the answers

What is the primary function of a promoter in the process of transcription?

<p>To initiate the binding of RNA polymerase and start transcription. (A)</p> Signup and view all the answers

What characterizes the promoter proximal elements of genes expressed at specific times?

<p>They are recognized only by activator proteins found in specific cell types or conditions. (C)</p> Signup and view all the answers

What is the primary function of the core promoter?

<p>It binds TBP and associated factors crucial for initiating basal transcription. (B)</p> Signup and view all the answers

Which portion of the promoter is primarily responsible for directly interacting with RNA polymerase?

<p>Core promoter (B)</p> Signup and view all the answers

In relation to the transcription initiation site, where are promoter sequences typically located?

<p>Directly upstream or at the 5' end (D)</p> Signup and view all the answers

Which of the following statements best describes the relationship between the promoter and the transcription start site?

<p>RNA polymerase binds at the promoter, where transcription begins at the TSS. (D)</p> Signup and view all the answers

Which component of the promoter is likely to influence long-range regulatory effects?

<p>Distal promoter (C)</p> Signup and view all the answers

Flashcards

Cis-regulatory elements (CREs)

Regions of non-coding DNA that regulate gene expression by binding to transcription factors.

Promoters

DNA sequences that act as binding sites for transcription factors to initiate transcription.

Enhancers

DNA sequences that can enhance gene transcription by binding to specific transcription factors.

Silencers

DNA sequences that suppress gene transcription by binding to specific transcription factors.

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Transcription factors

Proteins that bind to CREs and regulate gene expression. A single TF can control many genes.

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Gene Regulation

The process of regulating the amount and types of proteins produced by a cell.

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Cellular Function and mRNA

The mRNA molecules found in a cell reflect the function of that cell.

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Transcriptional Regulation

The primary control point for gene expression is at the start of transcription. This ensures efficient control because many proteins can be produced from a single mRNA molecule.

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Post-Transcriptional and Post-Translational Regulation

Gene regulation can also occur after transcription and translation.

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Transcriptional Regulation Efficiency

The most efficient way to regulate gene expression is at the transcriptional level because it controls the production of mRNA, which is the template for making many proteins.

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TATA Box

A DNA sequence located close to the promoter that is essential for transcription initiation.

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Transcription

The process of copying genetic information from DNA into RNA.

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General Transcription Machinery

A group of proteins that work together to initiate and carry out transcription.

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Cell Differentiation and Gene Expression

The differences between cell types arise because cells with the same genome (DNA) express different genes.

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Constitutive Genes

Genes that are always expressed in all cells, regardless of external conditions.

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Why are Constitutive Genes 'Always On'?

Proteins produced from constitutive genes are always needed by the cell for its basic operations and survival.

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Examples of Constitutive Genes

Examples include genes responsible for making parts of the cell's machinery, such as ribosomes and RNA polymerase.

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Examples of Constitutive Genes - Structural Proteins

These genes produce proteins that form the structural components of the cell, like the cytoskeleton.

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Examples of Constitutive Genes - Energy Production

These genes produce enzymes that catalyse glycolysis, the process of generating energy from glucose.

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Gene expression

Gene expression is the process of turning genes 'on' or 'off' to produce proteins.

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Cell specialization

Different cell types express different sets of genes, leading to unique functions.

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Alcohol dehydrogenase in liver cells

Liver cells produce alcohol dehydrogenase to remove alcohol from the bloodstream.

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Gene expression in neurons

Neurons in the brain don't remove toxins, so the genes for detoxification are turned off.

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Neurotransmitter genes in liver cells

Liver cells don't use neurotransmitters, so the genes for neurotransmitter production are turned off.

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What is the core promoter?

The core promoter is a DNA region where transcription of a gene starts. It controls whether a gene is transcribed.

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What is the TATA box?

The TATA box is a DNA sequence (5'-TATAAA-3') in the core promoter. It's the binding site for basal factors, including the TATA binding protein (TBP) and TBP associated factors.

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What are transcription factors?

Transcription factors are proteins that bind to promoter-proximal elements near the core promoter. They regulate gene expression by influencing how much RNA is made.

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Distance-Independent CREs

Enhancers and silencers can be located thousands of base pairs away from the gene they regulate.

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Reversible CREs

The location of enhancers and silencers can be reversed without affecting their ability to regulate gene expression.

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What are promoter-proximal elements?

Promoter-proximal elements are DNA sequences found upstream of the core promoter. These elements bind transcription factors that regulate the efficiency of transcription.

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CRE Binding

Enhancers and silencers bind to activator and repressor proteins, respectively, which modulate the basal level of transcription.

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Where are the promoter-proximal elements located?

The distance between the core promoter and the mRNA start site is about 100 base pairs. The promoter-proximal elements are found upstream, around 200 base pairs away.

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Core Promoter

The region of DNA closest to the transcription start site that directly binds to the transcription initiation complex.

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Proximal Promoter

A region of DNA upstream of the core promoter that assists in regulating transcription. It can interact with transcription factors to fine-tune gene expression.

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Distal Promoter

A DNA region that can be located far away from the core promoter, but can still regulate transcription. It often interacts with specific transcription factors to enhance or suppress gene expression.

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Transcription Start Site (TSS)

A DNA sequence within the promoter that is recognized by RNA polymerase and allows transcription to start.

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What are constitutive genes?

Constitutive genes are genes that are expressed in all cell types, regardless of the cell's specific function. They play a fundamental role in basic cellular processes and are essential for survival. These genes typically have common promoter proximal elements that recognize activator proteins found in all cells.

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What are regulated genes?

Genes that are expressed only in specific cell types or at particular times in development are called regulated genes. They have promoter proximal elements that recognize activator proteins that are only present in those specific cell types or at those particular times, leading to their expression only in those specific contexts.

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What are activator proteins?

Activator proteins are proteins that bind to promoter proximal elements and increase the rate of transcription. They play a vital role in regulating gene expression, allowing cells to respond to specific signals and adapt to changing conditions.

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Study Notes

Cis-regulatory elements (CREs)

  • Cis-regulatory elements (CREs) are regions of non-coding DNA (100 – 1000 bps in length) which regulate the transcription of neighbouring genes
  • Called 'cis' because they are on the same DNA strand as the genes they control
  • Typically regulate gene transcription by binding to regulatory proteins called transcription factors
  • A single transcription factor may bind to many CREs and hence control the expression of many genes
  • CREs carry out their function by integrating all regulatory elements at a specific time and place in the cell where this information is read, and an output given

Types of CREs

  • Promoters
  • Enhancers
  • Silencers

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Description

Test your knowledge on cis-regulatory elements (CREs) and their role in gene regulation. This quiz covers transcription factors, mRNA functions, and the transcription process, providing a comprehensive look into molecular biology principles. Perfect for students studying genetics or molecular biology.

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