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

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

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

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

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

What does a yellow spot on a DNA chip indicate?

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

What does a blank spot on a DNA chip indicate?

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

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

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

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

<p>In the absence of glucose (A)</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 (C)</p> Signup and view all the answers

What is the function of histone acetyltransferases?

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

What is the role of microRNAs in gene expression regulation?

<p>They inhibit translation (B)</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 (A)</p> Signup and view all the answers

What is the function of ubiquitin in protein regulation?

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

What is the role of histone deacetylases?

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

What is the function of RNA polymerase?

<p>It transcribes DNA into RNA (D)</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 (B)</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 (D)</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 (D)</p> Signup and view all the answers

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

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

What does a yellow spot on a DNA microarray indicate?

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

What does a black spot on a DNA microarray indicate?

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

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

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

Which type of regulatory protein prevents transcription of a gene?

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

Which structural polypeptide domain is found in most transcription regulators?

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

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

<p>Level of tryptophan (A)</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 (B)</p> Signup and view all the answers

What can acetyl groups on histones attract to promote transcription?

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

What is the main function of transcriptional regulators?

<p>To switch genes on and off (C)</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 (A)</p> Signup and view all the answers

What is the main function of transcriptional regulators?

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

Which type of regulatory protein prevents transcription of a gene?

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

What is the function of histone deacetylases?

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

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

<p>Ethanol utilization (C)</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 (A)</p> Signup and view all the answers

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

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

How can gene expression be controlled in eukaryotic cells?

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

What percentage of genes does a typical cell express?

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

Which structural polypeptide domain is found in most transcription regulators?

<p>All of the above (D)</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 (C)</p> Signup and view all the answers

What is the function of histone acetyltransferases?

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

What is the role of microRNAs in gene expression regulation?

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

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

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

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

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

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

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

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

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

What can acetyl groups on histones attract to promote transcription?

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

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

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

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

<p>Repressor proteins (D)</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. (D)</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 (C)</p> Signup and view all the answers

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

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

What does a blank spot on a DNA chip indicate?

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

What is the main function of transcriptional regulators?

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

What does a yellow spot on a DNA microarray indicate?

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

What is the function of ubiquitin in protein regulation?

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

What can acetyl groups on histones attract to promote transcription?

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

What does a black spot on a DNA microarray indicate?

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

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