Biology RNA Synthesis
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Questions and Answers

What is the primary difference between the sugar molecule found in RNA and DNA?

  • Glucose
  • Deoxyribose
  • Ribose (correct)
  • Fructose

    • What is the purpose of the sigma factor in prokaryotic transcription initiation?

  • To synthesize mRNA
  • To add nucleotides to the growing mRNA chain
  • To unwind DNA
  • To recruit RNA polymerase to the transcription start site (correct)

    • What is the primary function of heterogeneous nuclear RNA (hnRNA) in eukaryotic cells?

  • To encode proteins
  • To serve as a structural component of the ribosome
  • To undergo co-transcriptional and post-transcriptional modifications to form mRNA (correct)
  • To deliver amino acids to the ribosome

    • What is the direction of nucleotide addition during RNA synthesis?

    <p>5' → 3'</p> Signup and view all the answers

    What is the key difference in the sugar molecule between DNA and RNA?

    <p>RNA has ribose, while DNA has deoxyribose</p> Signup and view all the answers

    What is the function of ribosomal RNA (rRNA)?

    <p>To provide a structural and enzymatic component of the ribosome</p> Signup and view all the answers

    What is the main difference between prokaryotic and eukaryotic transcription?

    <p>Eukaryotic transcription involves additional modifications to the primary transcript, whereas prokaryotic transcription does not</p> Signup and view all the answers

    What is the average rate of mRNA synthesis in prokaryotes?

    <p>~50 nt/sec</p> Signup and view all the answers

    What is the function of transfer RNA (tRNA)?

    <p>To deliver amino acids to the ribosome</p> Signup and view all the answers

    What is the purpose of the promoter region in prokaryotic transcription?

    <p>To recruit RNA polymerase to the transcription start site</p> Signup and view all the answers

    What is the sequence of the transcript produced during transcription?

    <p>Complementary to the non-template strand of DNA</p> Signup and view all the answers

    What is the term for the process of converting the primary transcript (hnRNA) to mature mRNA in eukaryotic cells?

    <p>Post-transcriptional modification</p> Signup and view all the answers

    What is the primary mechanism of rho-dependent transcription termination?

    <p>Rho unwinds the DNA-RNA duplex using its helicase activity</p> Signup and view all the answers

    What is the term for the regions of DNA that are removed during RNA processing in eukaryotic cells?

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

    What is the function of RNA polymerase in prokaryotic transcription?

    <p>To synthesize mRNA</p> Signup and view all the answers

    Why do GC-rich sequences cause RNA polymerase to pause?

    <p>Because GC-rich sequences are hard to separate due to strong hydrogen bonds</p> Signup and view all the answers

    What is the base that replaces thymine in RNA?

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

    What is the function of the stem-loop structure in the mRNA transcript during rho-independent transcription termination?

    <p>It reduces the binding of mRNA to the DNA template</p> Signup and view all the answers

    What is the term for the flow of genetic information from DNA to RNA to proteins?

    <p>The central dogma of molecular biology</p> Signup and view all the answers

    What type of bonds join nucleotides in RNA?

    <p>Covalent phosphodiester bonds</p> Signup and view all the answers

    What is the purpose of rho protein in transcription termination?

    <p>To unwind the DNA-RNA duplex and release the RNA transcript</p> Signup and view all the answers

    What is the significance of the grey boxes in the given DNA sequence?

    <p>They represent the promoter site for RNA polymerase</p> Signup and view all the answers

    What is the function of the binding between sigma factor and the -10 and -35 boxes?

    <p>To position RNA polymerase at the transcription start site</p> Signup and view all the answers

    What is the location of the transcription start site?

    <p>Nucleotide 201</p> Signup and view all the answers

    What is the name of the region between nucleotides 58 and 97?

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

    What is the function of the sequences underlined by the straight and wiggly lines?

    <p>To initiate transcription</p> Signup and view all the answers

    What are the green and blue highlighted regions?

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

    Approximately how long is the transcript (how many nucleotides)?

    <p>700 nucleotides</p> Signup and view all the answers

    Would the mRNA sequence look like the original DNA sequence?

    <p>No, it would be complementary</p> Signup and view all the answers

    What is the function of the sigma factor?

    <p>To position RNA polymerase at the transcription start site</p> Signup and view all the answers

    What is the main difference between RNA polymerase II in eukaryotes and prokaryotes?

    <p>C-terminal domain</p> Signup and view all the answers

    Which of the following statements is NOT true about eukaryotic transcription?

    <p>RNA polymerase II synthesizes mRNA in the 5' to 3' direction</p> Signup and view all the answers

    What is the purpose of the spliceosome in eukaryotic cells?

    <p>To remove introns from pre-mRNA</p> Signup and view all the answers

    Which of the following processes occurs in the nucleus?

    <p>Transcription in eukaryotes</p> Signup and view all the answers

    What is the term for the regions of DNA that are removed during RNA processing in eukaryotic cells?

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

    What is the purpose of co-transcriptional/post-transcriptional modifications in eukaryotic cells?

    <p>To convert the primary transcript to mature mRNA</p> Signup and view all the answers

    Study Notes

    Transcription and RNA Synthesis

    • RNA differs from DNA in three key ways:
      • RNA is single-stranded
      • RNA contains ribose instead of deoxyribose
      • RNA contains uracil instead of thymine

    Types of RNA

    • Messenger RNA (mRNA) encodes proteins
    • Ribosomal RNA (rRNA) is a structural and enzymatic component of the ribosome
    • Transfer RNA (tRNA) delivers amino acids to the ribosome

    Transcription

    • The production of messenger RNA from a DNA template
    • RNA polymerase polymerizes ribonucleoside triphosphates into RNA
    • The mechanism of transcription has three parts:
      • Initiation
      • Elongation
      • Termination

    Transcription in Prokaryotes

    • Initiation:
      • Short recognition sequences (‘boxes’) in the promoter region serve to align RNA polymerase at the transcription start site
      • Sigma factor binds to the -10 (Pribnow) and -35 boxes, and recruits RNA polymerase to the transcription start site
    • Elongation:
      • RNA polymerase unwinds DNA as it moves
      • RNA polymerase reads the DNA template, synthesizing mRNA by adding complementary nucleotides
      • After the first few nucleotides are complete, the sigma factor dissociates
      • Average rate of synthesis = ~50 nt/sec
      • mRNA has the same sequence as the non-template (coding) strand of DNA
    • Termination:
      • Most common method of transcription termination in E. coli
      • Termination of transcription controlled by GC-rich stop sequences in DNA
      • mRNA transcript forms a stem loop, reducing binding of mRNA to DNA template
      • String of weak A-U pairings help detachment from DNA template

    Transcription in Eukaryotes

    • Key differences from prokaryotic transcription:
      • Existence of a nucleus, where transcription occurs
      • Presence of multiple RNA polymerases (I, II, and III)
      • RNA polymerase II synthesizes mRNA in the 5' to 3' direction
      • Co-transcriptional and post-transcriptional modifications occur in eukaryotic cells
    • Co-transcriptional and post-transcriptional modifications:
      • Addition of a 5' cap to eukaryotic pre-mRNA
      • Addition of a polyA tail to eukaryotic pre-mRNA
      • Splicing, which is the removal of introns from pre-mRNA
      • Export of processed mRNA into the cytoplasm

    Exons and Introns

    • Exons: regions of the primary transcript that are retained in the mature mRNA
    • Introns: regions of the primary transcript that are removed during splicing

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    Description

    Learn about the differences between RNA and DNA, types of RNA, and the process of transcription in this biology quiz.

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