Amino Acids: Catabolism and Synthesis

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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?

Aspartate and NH3 Signup and view all the answers

Which amino acid is converted to succinyl CoA?

Methionine Signup and view all the answers

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

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

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

GTP (+ ATP in eukaryotes) Signup and view all the answers

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

To bind the incoming aminoacyl-tRNA Signup and view all the answers

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

AMP + PPi Signup and view all the answers

What is the composition of the ribosome?

Proteins and rRNA Signup and view all the answers

What is the first step in the degradation of threonine?

Dehydration to alpha-ketobutyrate Signup and view all the answers

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

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

What is the end product of isoleucine degradation?

Succinyl CoA Signup and view all the answers

Which coenzyme is required for the transamination of BCAA?

Pyridoxal phosphate (PLP) Signup and view all the answers

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

It is a carrier compound for single carbon groups Signup and view all the answers

What happens when glucose is present along with lactose?

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

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

Attenuation Signup and view all the answers

What is the result of amino acid starvation?

Increased ppGpp production Signup and view all the answers

What is the effect of elevated levels of ppGpp?

Inhibition of rRNA synthesis Signup and view all the answers

What regulates operons for ribosomal proteins?

Excess of ribosomal proteins Signup and view all the answers

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

Increased Signup and view all the answers

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

Non-competitive Signup and view all the answers

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

Decreased Signup and view all the answers

What type of modification can activate or inactivate an enzyme?

Phosphorylation Signup and view all the answers

What is the purpose of isoenzymes in diagnostics?

To diagnose tissue damage Signup and view all the answers

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

Decreased activity Signup and view all the answers

What is the purpose of allosteric enzymes in regulation?

To catalyze rate-limiting steps Signup and view all the answers

What is the effect of lead on enzyme activity?

Decreases activity Signup and view all the answers

What is the purpose of phosphorylation in enzyme regulation?

To regulate enzyme activity Signup and view all the answers

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

Activates enzyme activity Signup and view all the answers

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

Spatial separation Signup and view all the answers

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

Amino acids from diet Signup and view all the answers

What is the primary function of the amino acid pool?

Balancing amino acid input and output Signup and view all the answers

How do amino acids leave the body?

As urea, ammonia, and other products Signup and view all the answers

What are the three sources of the amino acid pool?

Dietary proteins, body proteins, and simple intermediates 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?

Active site Signup and view all the answers

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

Transferases Signup and view all the answers

Which of the following is an example of substrate specificity?

Lipase hydrolyzing ester bonds in different TAGs 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?

Prosthetic group Signup and view all the answers

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

Apoenzyme Signup and view all the answers