cellular respiration

• The three pathways of aerobic respiration are:

  • Glycolysis
  • Citric acid Cycle
  • Electron transport chain
• ATP is required for the phosphorylation of glucose and intermediates during the energy investment phase of glycolysis. (2 ATP)
• The leads to the generation of more ATP during the energy pay-off stage (4 ATP) and results in a net gain of ATP (net gain of 2 ATP).
• Dehydrogenase enzymes remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH. This occurs in both glycolysis and the citric acid cycle.
• The hydrogen ions and electrons from NADH are passed to the electron transport chain on the inner mitochondrial membrane.
• In aerobic conditions, pyruvate is converted into an acetyl group that combines with coenzyme A forming acetyl coenzyme A. NADH and carbon dioxide are also formed during this process.
• In the citric cycle, the acetyl group from acetyl coenzyme A combines with oxaloacetate to form citrate.
• During a series of enzyme-controlled steps, citrate is gradually converted back into back into oxaloacetate which results in the generation on ATP and release of carbon dioxide.
• phosphorylation is an enzyme-controlled process by which a phosphate group is added to a molecule
• citric acid cycle takes place in the matrix of a mitochondria
• electron transport chain takes place on the cristae of a mitochondria
• • The electron transport chain is a series of carrier proteins attached to the inner mitochondrial membrane.
  • Electrons are passed along the electron transport chain releasing energy.
• • This energy allows hydrogen ions to be pumped across the inner mitochondrial membrane.
  • The flow of these ions back through the membrane protein ATP synthase results in the production of ATP.
  • Finally, the hydrogen ions and electrons combine with oxygen to form water.
• STAGE 1: GLYCOLYSIS

  A) Glucose

  B) Pyruvate

  C) dehydrogenase

  D) coenzyme

  E) NAD

  F) NADH

  
• STAGE 2: CAC

  A) Citrate

  B) NADH

  C) Coenzyme A

  D) NADH

  E) Oxaloacetate

  F) Acetyl coenzyme A

  
• 1. Glucose is broken down into pyruvate, and the removal of hydrogen ions and electrons by dehydrogenase enzymes releases ATP.
  2. Pyruvate progresses to the citric acid cycle if oxygen is available. Pyruvate is broken down into an acetyl group that combines with coenzyme A to be transferred to the citric acid cycle as acetyl coenzyme A.
  3. Acetyl (coenzyme A) combines with oxaloacetate to form citrate, followed by the enzyme-mediated steps of the cycle. This cycle results in the generation of ATP, the release of carbon dioxide and the regeneration of oxaloacetate.
• 4. Dehydrogenase enzymes remove hydrogen ions and electrons which are passed to the coenzymes NAD to form NADH in glycolysis and citric acid pathways. NADH release high-energy electrons to the electron transport chain on the mitochondrial membrane.

  5. The high-energy electrons pass along the chain, releasing energy. The energy is used to pump H ions across the inner mitochondrial membrane. The return flow of H ions drives ATP synthase and produces the bulk of the ATP generated by cellular respiration.

  6.  Oxygen combines with hydrogen ions and electrons to form water.