Mastering Gene Expression
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Questions and Answers

Which of the following is true about gene expression in human cells?

  • Cells can change the genes they express without altering their DNA sequence (correct)
  • A typical cell expresses all of its 25,000 genes
  • All human cells express the same RNAs and proteins
  • Gene expression can be controlled only at the transcriptional level

    • What is the most common control point for controlling gene expression?

  • Protein
  • RNA
  • Transcription (correct)
  • DNA

    • What percentage of genes does a typical cell express?

  • More than 90%
  • All of its genes
  • Around 50% (correct)
  • Less than 10%

    • How can gene expression be controlled in eukaryotic cells?

    <p>At multiple steps from DNA to protein</p> Signup and view all the answers

    How can we determine which genes are expressed in certain conditions?

    <p>By identifying all mRNAs produced</p> Signup and view all the answers

    What is the purpose of DNA chips (microarrays) in gene expression analysis?

    <p>To detect expressed mRNAs</p> Signup and view all the answers

    What does a yellow spot on a DNA chip indicate?

    <p>Expression of both cells' mRNAs</p> Signup and view all the answers

    What does a blank spot on a DNA chip indicate?

    <p>No gene expression</p> Signup and view all the answers

    In what conditions do yeast cells express genes for glucose utilization?

    <p>In the presence of glucose</p> Signup and view all the answers

    In what conditions do yeast cells express genes for ethanol utilization?

    <p>In the absence of glucose</p> Signup and view all the answers

    Which of the following is a mechanism for regulating eukaryotic gene expression after transcription?

    <p>Alternative splicing of pre-mRNA</p> Signup and view all the answers

    What is the function of histone acetyltransferases?

    <p>They change the charge of histone tails</p> Signup and view all the answers

    What is the role of microRNAs in gene expression regulation?

    <p>They inhibit translation</p> Signup and view all the answers

    What happens when iron levels are low in a cell?

    <p>IRP binds to IRE and blocks ribosome binding</p> Signup and view all the answers

    What is the function of ubiquitin in protein regulation?

    <p>It marks proteins for degradation</p> Signup and view all the answers

    What is the role of histone deacetylases?

    <p>They remove acetyl groups from histone tails</p> Signup and view all the answers

    What is the function of RNA polymerase?

    <p>It transcribes DNA into RNA</p> Signup and view all the answers

    What is the function of the RNA-induced silencing complex (RISC)?

    <p>It guides microRNAs to target mRNAs</p> Signup and view all the answers

    What is the purpose of alternative splicing?

    <p>To generate different mature mRNAs and proteins from the same gene</p> Signup and view all the answers

    What is the function of the iron regulatory protein (IRP)?

    <p>To bind to the iron-response element (IRE) in mRNA</p> Signup and view all the answers

    Which method is used to identify all mRNAs found in certain conditions?

    <p>DNA microarray</p> Signup and view all the answers

    What does a yellow spot on a DNA microarray indicate?

    <p>mRNAs equal to both conditions</p> Signup and view all the answers

    What does a black spot on a DNA microarray indicate?

    <p>Genes not expressed</p> Signup and view all the answers

    What determines the rate at which RNA polymerase initiates new rounds of transcription?

    <p>Specific transcription factors</p> Signup and view all the answers

    Which type of regulatory protein prevents transcription of a gene?

    <p>Repressor proteins</p> Signup and view all the answers

    Which structural polypeptide domain is found in most transcription regulators?

    <p>All of the above</p> Signup and view all the answers

    What regulates the activity of the polymerase transcribing the tryptophan operon?

    <p>Level of tryptophan</p> Signup and view all the answers

    What allows contact between an activator protein bound to an enhancer and a transcription complex bound to a promoter in eukaryotes?

    <p>Looping of DNA</p> Signup and view all the answers

    What can acetyl groups on histones attract to promote transcription?

    <p>Proteins that promote transcription</p> Signup and view all the answers

    What is the main function of transcriptional regulators?

    <p>To switch genes on and off</p> Signup and view all the answers

    Which of the following colors on a DNA microarray indicates genes that are expressed when glucose is utilized?

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

    What is the main function of transcriptional regulators?

    <p>To switch genes on/off</p> Signup and view all the answers

    Which type of regulatory protein prevents transcription of a gene?

    <p>Repressor protein</p> Signup and view all the answers

    What is the function of histone deacetylases?

    <p>To remove acetyl groups from histones</p> Signup and view all the answers

    In what conditions do yeast cells express genes for ethanol utilization?

    <p>Ethanol utilization</p> Signup and view all the answers

    What is the purpose of DNA chips (microarrays) in gene expression analysis?

    <p>To identify all mRNAs found in certain conditions</p> Signup and view all the answers

    What regulates the activity of the polymerase transcribing the tryptophan operon?

    <p>Tryptophan concentration</p> Signup and view all the answers

    How can gene expression be controlled in eukaryotic cells?

    <p>Through DNA methylation</p> Signup and view all the answers

    What percentage of genes does a typical cell express?

    <p>10%</p> Signup and view all the answers

    Which structural polypeptide domain is found in most transcription regulators?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is a mechanism for regulating eukaryotic gene expression after transcription?

    <p>MicroRNA inhibition of translation</p> Signup and view all the answers

    What is the function of histone acetyltransferases?

    <p>Add acetyl groups to histone tails</p> Signup and view all the answers

    What is the role of microRNAs in gene expression regulation?

    <p>Inhibit translation</p> Signup and view all the answers

    What determines the rate at which RNA polymerase initiates new rounds of transcription?

    <p>Transcriptional regulators</p> Signup and view all the answers

    What is the function of the iron regulatory protein (IRP)?

    <p>Inhibit translation in low iron conditions</p> Signup and view all the answers

    What is the purpose of DNA chips (microarrays) in gene expression analysis?

    <p>Detect mRNA sequences</p> Signup and view all the answers

    What is the most common control point for controlling gene expression?

    <p>Transcription initiation</p> Signup and view all the answers

    What can acetyl groups on histones attract to promote transcription?

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

    What is the function of the RNA-induced silencing complex (RISC)?

    <p>Promote mRNA degradation</p> Signup and view all the answers

    What regulates the activity of the polymerase transcribing the tryptophan operon?

    <p>Repressor proteins</p> Signup and view all the answers

    Which of the following is true about gene expression in human cells?

    <p>Human cells express approximately 50% of their 25,000 genes.</p> Signup and view all the answers

    What allows contact between an activator protein bound to an enhancer and a transcription complex bound to a promoter in eukaryotes?

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

    What determines the rate at which RNA polymerase initiates new rounds of transcription?

    <p>Transcriptional regulators</p> Signup and view all the answers

    What does a blank spot on a DNA chip indicate?

    <p>Genes not expressed</p> Signup and view all the answers

    What is the main function of transcriptional regulators?

    <p>To control gene expression at the DNA level</p> Signup and view all the answers

    What is the function of the iron regulatory protein (IRP)?

    <p>To bind to iron-responsive elements in mRNA</p> Signup and view all the answers

    What does a yellow spot on a DNA microarray indicate?

    <p>Genes expressed in both cells</p> Signup and view all the answers

    What is the function of ubiquitin in protein regulation?

    <p>To degrade proteins</p> Signup and view all the answers

    What can acetyl groups on histones attract to promote transcription?

    <p>Histone acetyltransferases</p> Signup and view all the answers

    What does a black spot on a DNA microarray indicate?

    <p>Genes not expressed</p> Signup and view all the answers

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