Lecture 12b
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Questions and Answers

During translation, which molecule is bound to IF2?

  • Pyrrolysine-tRNAprl
  • fMet-tRNAfmet (correct)
  • Met-tRNAmet
  • Sec-tRNA
  • Which molecule is introduced instead of methionine for the initiation codon?

  • Formyl methionine (fmet) (correct)
  • Sec
  • Leucine
  • Pyrrolysine
  • Which tRNA is formylated during translation?

  • tRNAmethionine
  • tRNAprl
  • tRNAfmet (correct)
  • tRNAsec
  • Which component of ribosomes in bacteria is responsible for catalyzing peptide bond formation?

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

    Which complex is formed by the 30S and 50S subunits in bacterial ribosomes?

    <p>Functional 70S ribosomes</p> Signup and view all the answers

    Which molecule serves as a source of energy during the initiation of translation in bacteria?

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

    What is the role of release factors (RF1, RF2, RF3) in the termination and ribosome recycling phase of translation?

    <p>Release of the polypeptide chain</p> Signup and view all the answers

    In eukaryotic ribosomes, what is the size of the small subunit?

    <p>40S</p> Signup and view all the answers

    What is the role of IF-3 during translation initiation in bacteria?

    <p>Keeps the 30S and 50S ribosomal subunits apart</p> Signup and view all the answers

    What is the function of IF-2 during translation initiation?

    <p>Recruits fMet-tRNA to the peptidyl site</p> Signup and view all the answers

    What is the significance of the Shine-Dalgarno sequence in translation initiation?

    <p>Guides mRNA to its correct position on the ribosome</p> Signup and view all the answers

    Which molecule is responsible for binding to IF-1, IF-3, and mRNA during translation initiation?

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

    In what way is an internal met codon processed?

    <p>Charged with met by met-tRNA synthetase</p> Signup and view all the answers

    What is the role of IF-2-GTP in the formation of the initiation complex in bacteria?

    <p>Recruits fmet-tRNAfmet and hydrolyzes GTP</p> Signup and view all the answers

    What serves as a signal for the initiation of protein synthesis in bacteria?

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

    What happens to IF-2-GTP in the last step of initiation complex formation?

    <p>It hydrolyzes to GDP and is released</p> Signup and view all the answers

    What is the function of Elongation Factor Tu (EF-Tu) in bacterial protein synthesis?

    <p>Binds aminoacyl tRNA and GTP</p> Signup and view all the answers

    Where does the aminoacyl tRNA-EF-Tu-GTP complex bind in the 70S initiation complex?

    <p>A site</p> Signup and view all the answers

    What occurs during the termination stage of protein synthesis?

    <p>Release of mRNA and protein dissociation</p> Signup and view all the answers

    In the elongation phase of protein synthesis, what is the main function of the ribosome?

    <p>Matching tRNAs to each codon</p> Signup and view all the answers

    What is the primary purpose of translocation during translation?

    <p>Movement of ribosome along mRNA</p> Signup and view all the answers

    What happens when a STOP codon is reached during protein synthesis?

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

    During protein synthesis, what role does ribosome recycling play?

    <p>Prepares for another round of protein synthesis</p> Signup and view all the answers

    What catalyzes the reaction of transferring the fmet group from tRNA in the P site to the amino acid in the A site during elongation in bacterial protein synthesis?

    <p>23S rRNA (ribozyme)</p> Signup and view all the answers

    What triggers the binding of termination factors (Release Factors) RF-1, RF-2, RF-3 in bacterial protein synthesis?

    <p>Stop codons UAA, UAG, or UGA</p> Signup and view all the answers

    What role does Ribosome Recycling Factor (RRF) play in bacterial protein synthesis termination?

    <p>Causes subunits of ribosome to dissociate</p> Signup and view all the answers

    What is the role of IF-3 during the formation of the initiation complex in bacterial translation?

    <p>Keeps 30S and 50S subunits apart</p> Signup and view all the answers

    How many ATP equivalents are used in the aminoacetylation step?

    <p>2</p> Signup and view all the answers

    How many ATP equivalents are used in the elongation step?

    <p>1</p> Signup and view all the answers

    How many ATP equivalents are used in the translocation step?

    <p>1</p> Signup and view all the answers

    How many ATP equivalents are used in the initiation step?

    <p>1</p> Signup and view all the answers

    How many ATP equivalents are used in the termination step?

    <p>1</p> Signup and view all the answers

    How many ATP equivalents are used in proofreading?

    <p>1</p> Signup and view all the answers

    How many ATP equivalents are needed to synthesize a polypeptide of 150 amino acids that required proofreading for 2 of its amino acids?

    <p>602</p> Signup and view all the answers

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