The tricarboxylic acid cycle

• What is the TCA cycle also known as?

  Krebs cycle
• What is the primary function of the TCA cycle?

  Final common pathway for catabolism
• What does the TCA cycle primarily produce?

  ATP in oxidative metabolism
• What role does the TCA cycle play in metabolism?

  Reservoir of chemical intermediates
• What are the main substrates entering the TCA cycle?

  • Carbohydrates
  • Triglycerides
  • Proteins
  • Glucose
  • Fatty acids
  • Amino acids
  • Small carbon chains
• How many reactions are in the TCA cycle?

  Eight reactions
• What initiates the TCA cycle?

  Condensation of Acetyl-CoA with oxaloacetate
• What happens to Acetyl-CoA during the TCA cycle?

  It enters and leaves as CO₂
• What is generated from NAD+ during the TCA cycle?

  NADH from electron transfer
• What is the significance of citrate in the TCA cycle?

  Citrate is a tri-carboxylic acid
• Which reaction is a rate-limiting step in the TCA cycle?

  Isocitrate Dehydrogenase reaction
• What does succinate thiokinase produce?

  GTP through substrate-level phosphorylation
• Where is succinate dehydrogenase located?

  Embedded in the inner mitochondrial membrane
• What does fumarase do in the TCA cycle?

  Hydrates fumarate to malate
• What is the final reaction of the TCA cycle catalyzed by?

  Malate Dehydrogenase
• How many carbon atoms enter and leave the TCA cycle as CO₂?

  Two carbon atoms enter and leave
• What is the maximum ATP yield from one glucose molecule in aerobic conditions?

  38 ATP
• What is produced during anaerobic metabolism of glucose?

  Lactate
• What is the role of oxygen in aerobic metabolism?

  Final electron acceptor in ETC
• What are the key regulatory points of the TCA cycle?

  • Citrate Synthase
  • Isocitrate Dehydrogenase
  • α-ketoglutarate Dehydrogenase
• What are the allosteric activators of the TCA cycle?

  ADP and Ca²⁺
• What inhibits the TCA cycle?

  ATP, GTP, and NADH
• How does the energy charge affect enzyme activity in the TCA cycle?

  High ATP/ADP ratio inhibits enzymes
• What happens during hypoxia or anoxia regarding the TCA cycle?

  Failure of oxidative phosphorylation occurs
• What is the function of the Electron Transport Chain (ETC)?

  • Accepts electrons from NADH and FADH₂
  • Passes electrons to generate ATP
  • Transports Ca²⁺ and generates heat
• What is the role of ATP synthase in the ETC?

  Enzyme responsible for ATP production
• What is the significance of the inner mitochondrial membrane?

  Site of ETC and ATP synthesis
• What are the key points regarding the TCA cycle's regulation?

  • Regulated enzymes: Citrate Synthase, Isocitrate Dehydrogenase, α-ketoglutarate Dehydrogenase
  • GTP, NADH, FADH₂ production
  • Acetyl CoA from glycolysis or β-oxidation
• What is the role of oxaloacetate in the TCA cycle?

  Used in gluconeogenesis to make glucose
• How does the TCA cycle contribute to amino acid biosynthesis?

  Amino acids can replenish TCA intermediates
• What is the amphibolic nature of the TCA cycle?

  Involves both anabolic and catabolic pathways
• What is the final product of the TCA cycle?

  Oxaloacetate
• What is the relationship between the TCA cycle and the electron transport chain?

  TCA cycle provides NADH and FADH2 for ETC
• How does the TCA cycle interact with fatty acid metabolism?

  Acetyl CoA from β-oxidation enters TCA cycle
• What is the role of reducing power from NADH and FADH₂?

  Used to generate ATP in ETC
• What is the importance of the outer mitochondrial membrane?

  Porous to small molecules
• How does the availability of intermediates affect the TCA cycle?

  Availability of oxaloacetate affects citrate synthesis
• What is the effect of ischemia on the TCA cycle?

  Interrupts blood supply affecting metabolism
• What is the primary function of the TCA cycle in metabolism?

  Final common pathway for energy production
• How does the TCA cycle relate to gluconeogenesis?

  Oxaloacetate is used to synthesize glucose