Energy 2

Aerobic Respiration:

• Definition: Aerobic respiration is the process by which cells convert glucose into energy in the presence of oxygen. It is the most efficient way to produce ATP.

• Location: Takes place in the mitochondria, specifically in the inner mitochondrial membrane and matrix.

• Energy Output: Yields approximately 36-38 ATP molecules per glucose molecule.

• Steps:

  1. Glycolysis: Initial breakdown of glucose in the cytoplasm.

  2. Krebs Cycle: Further breakdown of pyruvate in the mitochondrial matrix.

  3. Electron Transport Chain (ETC): Final stage where electrons are used to generate ATP.

Anaerobic Respiration:

• Definition: Anaerobic respiration occurs when cells produce energy without the presence of oxygen. It is less efficient than aerobic respiration.

• Location: Mainly in the cytoplasm.

• Energy Output: Yields only 2 ATP molecules per glucose molecule.

• Types: Common types include lactic acid fermentation and alcoholic fermentation.

Glycolysis:

• Definition: Glycolysis is the first stage of cellular respiration, where glucose is broken down into two molecules of pyruvate.

• Purpose:

  • Generates a small amount of ATP (net gain of 2 ATP).

  • Produces NADH, which carries high-energy electrons for the subsequent stages.

• Location: Takes place in the cytoplasm.

• Steps:

  1. Energy Investment Phase: Requires energy to activate glucose.

  2. Cleavage Phase: Glucose is split into two three-carbon molecules.

  3. Energy Liberation Phase: ATP and NADH are produced.

Lactic Acid Fermentation:

• Definition: Lactic acid fermentation is an anaerobic process that converts pyruvate into lactic acid.

• Purpose: Regenerates NAD+ to keep glycolysis running in the absence of oxygen.

• Location: Takes place in the cytoplasm.

• Steps:

  1. Glycolysis: Breaks down glucose into pyruvate.

  2. Conversion: Pyruvate is converted to lactic acid.

  3. NAD+ Regeneration: NADH is oxidized back to NAD+.

Krebs Cycle:

• Definition: The Krebs Cycle is the second stage of aerobic respiration, where acetyl-CoA is further broken down, producing NADH and FADH2.

• Purpose: Completes the oxidation of glucose, generating high-energy carriers.

• Location: Takes place in the mitochondrial matrix.

• Steps:

  1. Acetyl-CoA Formation: Pyruvate is converted to acetyl-CoA.

  2. Citric Acid Formation: Acetyl-CoA combines with oxaloacetate to form citric acid.

  3. Decarboxylation: Citric acid undergoes a series of reactions, releasing carbon dioxide.

  4. Energy Harvesting: NADH and FADH2 are produced.

  5. Regeneration: Oxaloacetate is regenerated for the next cycle.

Electron Transport Chain:

• Definition: The ETC is the final stage of aerobic respiration, where electrons from NADH and FADH2 are used to generate ATP.

• Location: Takes place in the inner mitochondrial membrane.

• Steps:

  1. Electron Movement: Electrons move through protein complexes.

  2. Proton Pumping: Energy from electron movement pumps protons across the membrane.

  3. ATP Synthesis: Protons flow back through ATP synthase, generating ATP.

  4. Oxygen's Role: Oxygen serves as the final electron acceptor, forming water.

Energy from Glucose:

• Process: Cellular respiration, which can be aerobic or anaerobic.

• Steps:

  1. Glycolysis: Initial breakdown of glucose in the cytoplasm.

  2. Aerobic Respiration:

     • Krebs Cycle: Further breakdown of pyruvate in the mitochondrial matrix.

     • Electron Transport Chain: ATP generation using high-energy electrons.

  3. Anaerobic Respiration:

     • Lactic Acid Fermentation: In the absence of oxygen, pyruvate is converted to lactic acid.

• Overall Output:

  • Aerobic Respiration: Produces more ATP and is highly efficient.

  • Anaerobic Respiration: Yields less ATP and is less efficient.