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

Which amino acid is converted to succinyl CoA?

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

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

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

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

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

What is the composition of the ribosome?

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

What is the first step in the degradation of threonine?

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

What is the end product of isoleucine degradation?

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

Which coenzyme is required for the transamination of BCAA?

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

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

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

What is the result of amino acid starvation?

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

What is the effect of elevated levels of ppGpp?

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

What regulates operons for ribosomal proteins?

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

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

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

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

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

What type of modification can activate or inactivate an enzyme?

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

What is the purpose of isoenzymes in diagnostics?

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

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

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

What is the purpose of allosteric enzymes in regulation?

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

What is the effect of lead on enzyme activity?

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

What is the purpose of phosphorylation in enzyme regulation?

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

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

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

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

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

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

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

What is the primary function of the amino acid pool?

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

How do amino acids leave the body?

<p>As urea, ammonia, and other products (A)</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 (A)</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 (C)</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 (D)</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 (D)</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 (D)</p> Signup and view all the answers

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

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

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