⚡️ 5. Krebs Cycle

• What is another name for the citric acid cycle?

  Tricarboxylic acid cycle
• Who is the citric acid cycle named after?

  Hans Krebs
• What is the primary function of the citric acid cycle?

  To degrade acetyl-CoA to carbon dioxide
• Where do the reactions of the citric acid cycle occur?

  In the matrix of mitochondria
• What do the released hydrogen atoms contribute to?

  They are oxidized to release energy
• What are the main stages of the citric acid cycle?

  • Begins with oxaloacetic acid
  • Acetyl-CoA combines with oxaloacetic acid to form citric acid
  • Water is added, carbon dioxide and hydrogen are released
  • Cycle regenerates oxaloacetic acid
• What is formed when acetyl-CoA combines with oxaloacetic acid?

  Citric acid
• What happens to the coenzyme A portion of acetyl-CoA?

  It is released for further use
• How many molecules of water are added during the citric acid cycle?

  Several molecules
• What are the net results of the citric acid cycle for each glucose molecule?

  4 CO2, 16 H atoms, 2 ATP
• How many ATP molecules are formed from one glucose molecule in the citric acid cycle?

  Two ATP molecules
• During which reaction is ATP formed in the citric acid cycle?

  From α-ketoglutaric acid to succinic acid
• What is the role of dehydrogenases in the citric acid cycle?

  • Catalyze the release of hydrogen atoms
  • Combine hydrogen with NAD+
  • Facilitate oxidative reactions to form ATP
• How many hydrogen atoms are released during glycolysis?

  Four hydrogen atoms
• What is the total number of hydrogen atoms released from one glucose molecule?

  24 hydrogen atoms
• How are hydrogen atoms released during the citric acid cycle?

  In packets of two by dehydrogenases
• What is the function of nicotinamide adenine dinucleotide (NAD+) in the cycle?

  Acts as a hydrogen carrier
• What happens to the four hydrogen atoms released during the citric acid cycle?

  They pass directly into the oxidative process
• What is the role of decarboxylases in the citric acid cycle?

  • Catalyze the release of carbon dioxide
  • Split carbon dioxide from the substrate
  • Transport carbon dioxide to the lungs
• How many stages in the citric acid cycle release carbon dioxide?

  Three stages
• Where is carbon dioxide transported after being released?

  To the lungs for expiration