Gene Regulation and Expression
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Questions and Answers

What is the function of the TATA box in eukaryotic gene regulation?

  • It breaks down RNA.
  • It enhances the rate of transcription.
  • It serves as a binding site for RNA polymerase. (correct)
  • It produces tRNA.

    • How do transcription factors influence gene expression?

  • By converting DNA into proteins.
  • By binding to sequences in the regulatory regions of eukaryotic genes. (correct)
  • By directly synthesizing RNA.
  • By breaking down mRNA.

    • What is one possible reason eukaryotic gene regulation is more complex?

  • Eukaryotes do not contain DNA.
  • Eukaryotes express genes in different specialized cells. (correct)
  • Eukaryotes do not undergo gene regulation.
  • Eukaryotes have fewer types of cells.

    • What role do RNA-binding proteins play in gene expression?

    <p>They block access to genes.</p> Signup and view all the answers

    Why is cell specialization important in multicellular organisms?

    <p>It enables the differentiation of cells to perform various functions.</p> Signup and view all the answers

    What molecule binds to the operator to prevent transcription of the lac operon genes?

    <p>Lac repressor</p> Signup and view all the answers

    What happens to the lac repressor when lactose is present?

    <p>It falls off the operator</p> Signup and view all the answers

    Which of the following is the function of the lac operon in E. coli?

    <p>Transporting lactose and breaking it down into glucose and galactose</p> Signup and view all the answers

    Where does RNA polymerase bind to begin transcription?

    <p>Promoter</p> Signup and view all the answers

    Why is it important for E. coli to switch the lac genes on and off?

    <p>To save energy when lactose is not available</p> Signup and view all the answers

    What is the role of the repressor protein in the absence of lactose?

    <p>It binds to the operator preventing transcription</p> Signup and view all the answers

    Which compound is necessary for the lac repressor to change its shape and fall off the operator?

    <p>Lactose</p> Signup and view all the answers

    Which of the following molecules is directly responsible for initiating transcription of the lac operon genes?

    <p>RNA polymerase</p> Signup and view all the answers

    What role do DNA-binding proteins play in prokaryotic gene regulation?

    <p>They regulate genes by controlling transcription</p> Signup and view all the answers

    Why is it beneficial for bacteria to regulate gene expression?

    <p>To conserve energy and resources</p> Signup and view all the answers

    What is an operon in the context of prokaryotic gene regulation?

    <p>A group of genes regulated together</p> Signup and view all the answers

    What molecule must E. coli break apart to utilize as food, as illustrated by the lac operon?

    <p>Lactose</p> Signup and view all the answers

    What would be wasteful for a bacterium to produce if it can obtain the molecule from its environment?

    <p>Enzymes to make a molecule</p> Signup and view all the answers

    What are the three genes involved in the lac operon of E. coli responsible for?

    <p>Breaking apart lactose</p> Signup and view all the answers

    How does E. coli decide which genes to express at any given time?

    <p>By using DNA-binding proteins that control transcription</p> Signup and view all the answers

    Which of the following statements about master control genes is correct?

    <p>They can trigger patterns of development and differentiation in cells.</p> Signup and view all the answers

    What is the primary function of the lac operon in E. coli?

    <p>To control the breakdown of lactose</p> Signup and view all the answers

    How do cells regulate gene expression through chromatin state?

    <p>By attaching chemical groups to DNA and histone proteins.</p> Signup and view all the answers

    What impact does the attachment of methyl groups have on chromatin?

    <p>It condenses chromatin, shutting down gene expression.</p> Signup and view all the answers

    Which of the following is an example of epigenetic regulation?

    <p>Chemical marks on chromatin</p> Signup and view all the answers

    What effect does the attachment of acetyl groups have on gene expression?

    <p>It opens chromatin up for transcription and enhances gene expression.</p> Signup and view all the answers

    Which of the following accurately describes epigenetic marks?

    <p>They influence gene expression without changing DNA sequences.</p> Signup and view all the answers

    Which of these statements is true about the development stages of a caterpillar, pupa, and butterfly?

    <p>They have the same genes but different epigenetic marks regulating gene expression at each stage.</p> Signup and view all the answers

    What is the role of nucleosomes in gene expression?

    <p>Nucleosomes form chromatin, which can either block or allow gene expression based on its packing.</p> Signup and view all the answers

    What do homeotic genes regulate?

    <p>The organs that develop in specific parts of the body</p> Signup and view all the answers

    Which type of genes code for transcription factors that activate other genes important in cell development?

    <p>Homeobox genes</p> Signup and view all the answers

    What did Edward B. Lewis demonstrate regarding homeotic genes?

    <p>They control the identities of body parts in fruit fly embryos</p> Signup and view all the answers

    What is the function of Hox genes in humans?

    <p>To tell cells how to differentiate as the body grows</p> Signup and view all the answers

    What sequence do molecular studies show is shared by homeotic genes?

    <p>A 180-base DNA sequence</p> Signup and view all the answers

    How are Hox genes arranged in the DNA of animals?

    <p>From head to tail</p> Signup and view all the answers

    What does the process of differentiation in an embryo lead to?

    <p>Specialized tissues and organs</p> Signup and view all the answers

    Which genes determine the identities of each segment of a fly’s body?

    <p>Hox genes</p> Signup and view all the answers

    Which factor does not impact gene expression?

    <p>pH level</p> Signup and view all the answers

    In E. coli, when is the lac operon switched on?

    <p>When lactose is the sole food source</p> Signup and view all the answers

    At what temperature range does the gene controlling fur color in Himalayan rabbits produce black fur?

    <p>Between 15°C and 25°C</p> Signup and view all the answers

    At what temperature is the gene controlling fur color in Himalayan rabbits inactive across the entire body?

    <p>Above 30°C</p> Signup and view all the answers

    Which of the following is not a mechanism by which transcription factors regulate eukaryotic gene expression?

    <p>Inhibiting protein synthesis directly</p> Signup and view all the answers

    How do master control genes contribute to organism development?

    <p>They control the expression of other genes</p> Signup and view all the answers

    Study Notes

    Gene Regulation and Expression

    • Gene regulation is essential for cells to conserve energy and resources by controlling which genes are expressed.

    Prokaryotic Gene Regulation

    • Prokaryotes regulate genes by controlling transcription using DNA-binding proteins that switch genes on or off.
    • The lac operon in E. coli is an example of a group of genes regulated together.
    • The lac operon is turned on or off by the lac repressor protein, which binds to the operator region.

    The Lac Operon

    • The lac operon consists of three genes that code for proteins involved in lactose breakdown.
    • The lac operon is turned off when the lac repressor binds to the operator region, preventing RNA polymerase from transcribing the genes.
    • The presence of lactose changes the shape of the lac repressor, allowing RNA polymerase to bind and transcribe the genes.

    Master Control Genes and Epigenetics

    • Master control genes are switches that trigger patterns of development and differentiation in cells and tissues.
    • Epigenetic mechanisms control gene expression by adding chemical marks to chromatin, which can compact or open up chromatin structure.
    • Chromatin compactness affects gene expression, with compact chromatin blocking gene expression and open chromatin enhancing gene expression.

    Environmental Influences

    • Environmental factors such as temperature, salinity, and nutrient availability influence gene expression.
    • The lac operon is switched on only when lactose is the sole food source in E. coli's environment.

    Hox Genes and Body Development

    • Homeotic genes, including Hox genes, regulate the identities of body parts in embryos.
    • Hox genes code for transcription factors that activate genes important in cell development and differentiation.
    • Hox genes are arranged in a specific order in the genome, corresponding to their expression from anterior to posterior in the body.

    Homeobox Genes

    • Homeobox genes share a similar 180-base DNA sequence, known as the homeobox.
    • Homeobox genes code for transcription factors that regulate cell development and differentiation.

    Genetic Control of Development

    • Regulating gene expression is crucial during development to control cell differentiation and organ formation.

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    Description

    Explore how genes are regulated in prokaryotic and eukaryotic cells, and how they control development in multicellular organisms. Learn key terms like operon, operator, differentiation, and homeotic genes.

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