Eukaryotic Transcription Overview
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Questions and Answers

Which RNA polymerase is specifically responsible for transcribing mRNA in eukaryotic cells?

  • RNA Polymerase I
  • RNA Polymerase III
  • RNA Polymerase II (correct)
  • RNA Polymerase IV

    • What is the role of TFIIB in the transcription initiation process?

  • Recruit RNA Polymerase I
  • Binds to the TATA element (correct)
  • Stabilizes RNA Polymerase II
  • Interacts with TBP and TATA sequence

    • Which transcription factor contains the TATA Binding Protein (TBP)?

  • TFIIE
  • TFIIF
  • TFIID (correct)
  • TFIIB

    • How many RNA polymerase enzymes are found in eukaryotic cells?

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

    What is the function of TFIIE during transcription initiation?

    <p>Stabilizes the TFIID binding (C)</p> Signup and view all the answers

    Which factor assists RNA Polymerase II in reaching the promoter region?

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

    What is the approximate location of the TATA element relative to the transcription start site?

    <p>80 nucleotides upstream (A)</p> Signup and view all the answers

    Which transcription factor is NOT part of the TFII complex?

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

    What characteristic change does TBP cause to the DNA upon binding?

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

    Which of the following statements is true regarding transcription factors in eukaryotic cells?

    <p>They differ by their specific roles in transcription initiation (C)</p> Signup and view all the answers

    What is the primary function of the ATPase activity within TFIIH?

    <p>Melts the promoter and transitions to the open complex (D)</p> Signup and view all the answers

    Which subunits of TFIIH are responsible for kinase activity?

    <p>Seven subunits are involved in phosphorylation (C)</p> Signup and view all the answers

    What role does TFIIE play during transcription elongation?

    <p>Regulates and stimulates the rate of transcription (A)</p> Signup and view all the answers

    What is the function of the 5' cap on mRNA?

    <p>Protects mRNA from ribonuclease degradation (A)</p> Signup and view all the answers

    During transcription termination, which proteins interact with the C-terminal domain of RNA Polymerase II?

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

    What enzymatic process does Poly(A) polymerase perform?

    <p>Adds adenine residues to the 3' end of mRNA (A)</p> Signup and view all the answers

    What happens to CSTF after the mRNA is cleaved?

    <p>It leaves the mRNA after cleavage (C)</p> Signup and view all the answers

    Which of the following best describes the activity of methyl transferase during the 5' capping process?

    <p>It attaches a methyl group to the guanine nucleotide (C)</p> Signup and view all the answers

    Which enzyme is responsible for attaching guanine to the mRNA during 5' capping?

    <p>Guanine transferase (C)</p> Signup and view all the answers

    What is the effect of TFIIE on transcription at different DNA sequences?

    <p>It can regulate transcription speed, faster at some sequences and slower at others. (A)</p> Signup and view all the answers

    Flashcards

    RNA Polymerase II

    The enzyme responsible for transcribing messenger RNA (mRNA) in eukaryotic cells.

    Transcription Factors

    Proteins that are critical for initiating transcription in eukaryotes.

    TATA element

    A specific sequence within the promoter region of a gene that is recognized and bound by the TATA Binding Protein (TBP).

    TFIIB

    A transcription factor that binds to the TATA element in the promoter region ensuring proper positioning of RNA polymerase II.

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    TFIID

    A complex of proteins that binds to the TATA box enabling RNA Polymerase II to bind to the promoter.

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    TBP

    A protein within TFIID that binds to the TATA element, which bends DNA for initiating transcription.

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    TFIIE

    A transcription factor that helps stabilize TFIID's binding to the promoter.

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    TFIIF

    A transcription factor which helps recruit RNA polymerase II to the promoter region.

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    Pre-initiation Complex

    Transcription factors, alongside RNA polymerase II, form an assembly at the promoter region ready to initiate transcription.

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    Promoter

    A region of DNA that is located upstream of the transcription start site and contains the TATA element and other regulatory sequences. It is essential for the initiation of transcription.

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    TFIIH's Helicase Activity

    The process of melting the promoter sequence and transitioning the pre-initiation complex to the open complex.

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    TFIIH's Kinase Activity

    The process of phosphorylating the C-terminal domain (CTD) of RNA Polymerase II, initiating promoter escape and transcription elongation.

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    Elongation Factors

    A group of proteins that assist in the process of transcribing DNA into RNA.

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    5' Capping

    The process of adding a protective 5' cap to mRNA during elongation, which helps with its recruitment to the ribosome.

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    RNA Triphosphatase

    An enzyme that removes the terminal gamma phosphate of the nucleotide in the 5' capping process.

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    Guanine Transferase

    An enzyme that attaches guanine to the beta phosphate of the first nucleotide in the 5' capping process.

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    Methyl Transferase

    An enzyme that adds a methyl group to the guanine nucleotide in the 5' capping process.

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    CSTF (Cleavage Stimulation Factor)

    A protein that helps with the cleavage and polyadenylation of mRNA during transcription termination.

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    Study Notes

    Eukaryotic Transcription

    • RNA polymerase is the enzyme responsible for transcription

      • Prokaryotes have one RNA polymerase enzyme
      • Eukaryotes have three RNA polymerase enzymes
      • RNA Polymerase II is responsible for transcribing mRNA

    • Transcription Factors are proteins required for transcription initiation

      • Designated as TF (transcription factor)
      • TFII indicates a transcription factor for RNA Polymerase II
      • The letter following TFII indicates the specific function
      • Examples:
        • TFIIA
        • TFIIB
        • TFIID
        • TFIIE
        • TFIIF
        • TFIIH

    Transcription Initiation

    • TFIIB binds to the TATA element (Tata box) within the promoter
      • The promoter is approximately 40 nucleotides long upstream and downstream of the transcription start site.
      • The TATA element is 80 nucleotides upstream of the transcription start site.
    • TFIID contains TBP (TATA Binding Protein), which binds to the TATA sequence
      • Bends DNA by 80 degrees
      • This bending aids in the binding of other transcription factors
    • TFIIE stabilizes TFIID binding to the promoter.
    • TFIIF interacts with TBP and the promoter downstream of the TATA element, assisting RNA polymerase II recruitment to the promoter.
    • TFIIF binds the promoter with RNA polymerase II, enabling RNA polymerase II recruitment.
    • TFIIE assists in the formation of the pre-initiation complex
    • TFIIH is a large complex with 9 subunits
      • Two subunits possess ATPase activity
        • Functioning as helicase, TFIIH melts the promoter
        • Transitions the pre-initiation complex to the open complex
      • Seven subunits exhibit kinase activity
        • Phosphorylates the C-terminal domain (CTD) of RNA Polymerase II
        • Initiates promoter escape and transcription elongation

    Transcription Elongation

    • Elongation Factors aid in transcription elongation
      • TFIIE is recruited by transcription activators
      • Phosphorylates serine residues on the CTD of polymerase, stimulating elongation
      • TFIIE regulates transcription rate
        • Varied rate at different DNA sequences
        • Prevents polymerase pausing and encourages movement

    5' Capping

    • Occurs during elongation
    • Protection and mRNA ribosome recruitment
      • Occurs 5' to 3'
      • RNA triphosphatase removes terminal gamma phosphate
      • Guanine transferase attaches guanine to the beta phosphate of the first nucleotide
      • Methyl transferase adds a methyl group to the guanine nucleotide
      • This 5' cap enables mRNA ribosome recruitment for translation initiation

    Transcription Termination

    • RNA Polymerase II's CTD interacts with CSTF (Cleavage Stimulation Factor) and CPSF (Cleavage and Polyadenylation Specificity Factor)
    • These proteins are recruited to the mRNA at the gene end by the CTD
    • CSTF leaves the mRNA after cleavage
    • CPSF recruits Poly(A) polymerase
      • Adds ~200-250 adenine residues to the 3' end, forming the poly(A) tail
      • Uses ATP
    • Poly(A) binding protein binds the poly(A) tail, preventing degradation
    • CPSF is released from the mRNA

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    Description

    This quiz explores the key components of eukaryotic transcription, focusing on the role of RNA polymerase and transcription factors. You'll learn about the different RNA polymerases in eukaryotes and the function of key transcription factors like TFIIB and the TATA element. Test your understanding of the transcription initiation process!

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