CELLULAR RESPIRATIONNNNNNNNNN

Stages of Cellular Respiration:

1. Glycolysis

   • Where It Happens: In the cytoplasm of the cell.

   • What Happens: 1 glucose molecule is broken down into 2 pyruvate molecules.

   • Inputs:

     • 1 Glucose molecule

     • 2 NAD+ (electron carriers)

   • Outputs:

     • 2 Pyruvate molecules

     • 2 ATP molecules

     • 2 NADH molecules

2. Transition Step (Pyruvate Oxidation)

   • Where It Happens: In the mitochondrial matrix.

   • What Happens: Each pyruvate is converted into Acetyl-CoA. During this process, one carbon atom from pyruvate is released as CO2, and NAD+ is reduced to NADH.

   • Inputs:

     • 2 Pyruvate molecules

     • 2 NAD+

     • 2 Coenzyme A (CoA)

   • Outputs:

     • 2 Acetyl-CoA

     • 2 NADH

     • 2 CO2 (as byproduct)

3. Krebs Cycle (Citric Acid Cycle)

   • Where It Happens: In the mitochondria.

   • What Happens: Each Acetyl-CoA enters the Krebs cycle and is metabolized for energy. The cycle produces electron carriers and ATP while releasing CO2 as a waste product. The cycle involves multiple steps that regenerate oxaloacetate and produce energy-rich molecules.

   • Inputs:

     • 2 Acetyl-CoA

     • 6 NAD+

     • 2 FAD

   • Outputs:

     • 4 CO2

     • 2 ATP

     • 6 NADH

     • 2 FADH2

4. Electron Transport Chain (ETC)

   • Where It Happens: In the inner mitochondrial membrane.

   • What Happens: The electron transport chain uses electrons from NADH and FADH2 to create a proton gradient across the membrane. The energy from this proton gradient is used to produce ATP through oxidative phosphorylation.

   • Inputs:

     • 10 NADH (from glycolysis and Krebs cycle)

     • 2 FADH2 (from Krebs cycle)

     • O2 (oxygen)

   • Outputs:

     • Approximately 34 ATP molecules

     • H2O (water as a byproduct)

     • NAD+ and FAD (regenerated for reuse)