Molecular Biology Lecture 5: RNA Processing and Translation
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Questions and Answers

What is required to be removed before degradation of eukaryotic mRNA can proceed?

  • Cap
  • Start codon
  • Poly (A) tail (correct)
  • Exonuclease

    • Which enzyme is responsible for removing the cap during degradation of eukaryotic mRNA?

  • Exonuclease Xrn1
  • tRNA molecule
  • Decapping protein (Dcp1) (correct)
  • Poly (A)-binding protein

    • What determines the stability of eukaryotic mRNA?

  • Start codon
  • Poly (A) tail
  • Exonuclease
  • Destabilizing sequences (correct)

    • Which subunit binds to the messenger RNA during translation?

    <p>30S subunit</p> Signup and view all the answers

    What initiates the coding sequence in eukaryotic mRNA translation?

    <p>Start codon</p> Signup and view all the answers

    What are the three major types of processing that RNA molecules undergo?

    <p>Base modification, cleavage, splicing</p> Signup and view all the answers

    Which of the following statements about eukaryotic mRNA processing is TRUE?

    <p>Eukaryotic mRNA contains a cap and tail, and undergoes base modification</p> Signup and view all the answers

    What is the main function of non-coding RNA?

    <p>To perform active roles other than encoding proteins</p> Signup and view all the answers

    Which process involves the addition of a cap and tail to eukaryotic mRNA?

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

    What type of RNAs are used not to carry information but to perform active roles?

    <p>non-coding RNAs</p> Signup and view all the answers

    Which statement is FALSE regarding RNA processing?

    <p>RNA undergoes capping and tailing but not splicing</p> Signup and view all the answers

    What is the role of the Poly(A) tail in eukaryotic mRNA?

    <p>Adds stability and protection to the mRNA</p> Signup and view all the answers

    What is the function of cleavage stimulation factor (CST) in eukaryotic mRNA processing?

    <p>Binds to GU-rich tract</p> Signup and view all the answers

    What happens to prokaryotic mRNA when a poly(A) tail is added?

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

    What is the function of the spliceosome in mRNA processing?

    <p>Joins exons together after intron removal</p> Signup and view all the answers

    Which component forms a small nuclear ribonucleoprotein (snRNP) in the spliceosome?

    <p>Small nuclear RNA (snRNA)</p> Signup and view all the answers

    What is the main difference between the poly(A) tail function in eukaryotes and prokaryotes?

    <p>Adds stability in eukaryotes, promotes degradation in prokaryotes</p> Signup and view all the answers

    What is the role of initiation factor 3 (IF-3) during translation initiation?

    <p>It prevents the large ribosomal subunit from binding during initiation.</p> Signup and view all the answers

    Which molecule pairs with its complementary nucleotides in the 16S rRNA during translation initiation?

    <p>Shine-Dalgarno sequence</p> Signup and view all the answers

    In eukaryotic cells, what plays a critical role similar to Shine-Dalgarno sequence in bacterial translation initiation?

    <p>Cap at the 5' end of mRNA</p> Signup and view all the answers

    What is the function of elongation factor G (EF-G) in translation elongation?

    <p>Allows the ribosome to translocate down mRNA</p> Signup and view all the answers

    Why does protein synthesis terminate when a termination codon is encountered?

    <p>Release factors cause the dissociation of ribosomal subunits.</p> Signup and view all the answers

    What happens during translocation in translation elongation?

    <p>The ribosome moves down mRNA in the 5'—3' direction.</p> Signup and view all the answers

    What are the three release factors in E. coli that form a complex with GTP and bind to the ribosome?

    <p>RF1, RF2, and RF3</p> Signup and view all the answers

    Which release factor recognizes the termination codons UGA and UAA in E. coli?

    <p>RF1</p> Signup and view all the answers

    In eukaryotic cells, what is the function of eRF2?

    <p>Binds GTP and stimulates the release of the polypeptide from the ribosome</p> Signup and view all the answers

    What feature distinguishes the termination process in eukaryotic cells from prokaryotic cells?

    <p>Eukaryotic release factor eRF1 recognizes all three termination codons, unlike in prokaryotic cells</p> Signup and view all the answers

    What can affect the initiation of translation according to the text?

    <p>The availability of ribosomes, tRNAs, initiation and elongation factors</p> Signup and view all the answers

    How do posttranslational modifications affect eukaryotic proteins?

    <p>They affect the transport, function, and activity of proteins</p> Signup and view all the answers

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