Amino Acids: Catabolism and Synthesis
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Questions and Answers

Which amino acid is converted to α-ketoglutarate via glutamate?

  • Histidine (correct)
  • Asparagine
  • Arginine
  • Glutamine

    • What is the byproduct of the hydrolysis of glutamine?

  • Glutamate and CO2
  • Alanine and NH3
  • Aspartate and NH3
  • Glutamate and NH3 (correct)

    • Which amino acid is converted to pyruvate through transamination by ALT?

  • Threonine
  • Glycine
  • Alanine (correct)
  • Serine

    • What is the byproduct of the hydrolysis of asparagine?

    <p>Aspartate and NH3</p> Signup and view all the answers

    Which amino acid is converted to succinyl CoA?

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

    What is the function of aminoacyl-tRNA synthetase in protein synthesis?

    <p>To catalyze the reaction of binding amino acids to tRNA and then cleave ATP to AMP + PPi</p> Signup and view all the answers

    What is the energy source required for initiation in protein synthesis?

    <p>GTP (+ ATP in eukaryotes)</p> Signup and view all the answers

    What is the purpose of the A site on the ribosome?

    <p>To bind the incoming aminoacyl-tRNA</p> Signup and view all the answers

    What is the byproduct of the reaction catalyzed by aminoacyl-tRNA synthetase?

    <p>AMP + PPi</p> Signup and view all the answers

    What is the composition of the ribosome?

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

    What is the first step in the degradation of threonine?

    <p>Dehydration to alpha-ketobutyrate</p> Signup and view all the answers

    Which enzyme complex is responsible for the oxidative decarboxylation of alpha-keto acids derived from BCAA?

    <p>Branched chain alpha-keto acid dehydrogenase (BCKD) complex</p> Signup and view all the answers

    What is the end product of isoleucine degradation?

    <p>Succinyl CoA</p> Signup and view all the answers

    Which coenzyme is required for the transamination of BCAA?

    <p>Pyridoxal phosphate (PLP)</p> Signup and view all the answers

    What is the role of Tetrahydrofolate (THF) in one-carbon metabolism?

    <p>It is a carrier compound for single carbon groups</p> Signup and view all the answers

    What happens when glucose is present along with lactose?

    <p>Glucose prevents formation of cAMP, and transcription of lactose genes is negligible</p> Signup and view all the answers

    What is the mechanism of regulation of Trp operon when Trp is plentiful?

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

    What is the result of amino acid starvation?

    <p>Increased ppGpp production</p> Signup and view all the answers

    What is the effect of elevated levels of ppGpp?

    <p>Inhibition of rRNA synthesis</p> Signup and view all the answers

    What regulates operons for ribosomal proteins?

    <p>Excess of ribosomal proteins</p> Signup and view all the answers

    What is the effect of a competitive inhibitor on the Km value of an enzyme?

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

    What type of enzyme inhibition occurs when an inhibitor binds to a site other than the active site?

    <p>Non-competitive</p> Signup and view all the answers

    What is the effect of a non-competitive inhibitor on the Vmax of an enzyme?

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

    What type of modification can activate or inactivate an enzyme?

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

    What is the purpose of isoenzymes in diagnostics?

    <p>To diagnose tissue damage</p> Signup and view all the answers

    What is the effect of a high Km value on enzyme activity?

    <p>Decreased activity</p> Signup and view all the answers

    What is the purpose of allosteric enzymes in regulation?

    <p>To catalyze rate-limiting steps</p> Signup and view all the answers

    What is the effect of lead on enzyme activity?

    <p>Decreases activity</p> Signup and view all the answers

    What is the purpose of phosphorylation in enzyme regulation?

    <p>To regulate enzyme activity</p> Signup and view all the answers

    What is the effect of a substrate on an allosteric enzyme?

    <p>Activates enzyme activity</p> Signup and view all the answers

    What is the primary difference in transcription and translation between prokaryotes and eukaryotes?

    <p>Spatial separation</p> Signup and view all the answers

    What is the primary source of nitrogen in the human body?

    <p>Amino acids from diet</p> Signup and view all the answers

    What is the primary function of the amino acid pool?

    <p>Balancing amino acid input and output</p> Signup and view all the answers

    How do amino acids leave the body?

    <p>As urea, ammonia, and other products</p> Signup and view all the answers

    What are the three sources of the amino acid pool?

    <p>Dietary proteins, body proteins, and simple intermediates</p> Signup and view all the answers

    What is the term for a special pocket or cleft formed by folding of protein, containing amino acid side chains that participate in substrate binding and catalysis?

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

    What type of enzymes catalyze the transfer of a functional group from one substrate to another?

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

    Which of the following is an example of substrate specificity?

    <p>Lipase hydrolyzing ester bonds in different TAGs</p> Signup and view all the answers

    What is the term for a coenzyme that is permanently associated with an enzyme and returned to its original form?

    <p>Prosthetic group</p> Signup and view all the answers

    What is the term for an enzyme that is inactive without a nonprotein component?

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

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