Cellular Respiration Overview

Purpose of Cellular Respiration

Occurs in the cytosol of the cell, not in mitochondria.
Can occur without oxygen.
Performed by nearly all organisms, suggesting ancestral origin.
Catabolism of Glucose:
- Produces pyruvate, 2 NADH, and a small amount of ATP.
- Pyruvate undergoes oxidation to form acetyl CoA before entering Krebs Cycle.

Takes place in the inner mitochondrial matrix.
Pyruvate breaks down into carbon dioxide and water.
Key Outputs:
- ATP
- Carbon Dioxide (byproduct)
- NADH and FADH2 (coenzymes for electron transport)
Described as a "cycle" because it regenerates the molecule that starts the cycle.
Oxidation of Intermediates: Loss of electrons for transfer to electron transport chain.

Occurs across the inner mitochondrial membrane.
ATP Synthase is the key enzyme (a proton pump) that generates ATP.
Process:
- Electrons pass through a series of reactions, creating an electrochemical gradient.
- Protons accumulate on one side of the membrane, powering ATP synthase.
- Results in ATP synthesis from ADP.
Final Electron Acceptor: Oxygen, which creates water as a byproduct.
This stage produces about 34 ATP molecules.

Glycolysis releases energy; small amounts of ATP and NADH are generated.
Pyruvate is transported to mitochondria, producing acetyl CoA for the Krebs Cycle.
Krebs Cycle releases carbon dioxide and synthesizes more ATP.
Electrons from glycolysis and Krebs Cycle transferred by NADH and FADH2 to the Electron Transport Chain.
Gradient and Proton Flow: Establishes a gradient for ATP synthesis via oxidative phosphorylation.
Total ATP production is significant at this stage.

Other molecules are involved in cellular respiration but are not essential to memorize for exams.
The provided drawing notes accompany this summary for visual learners.

This summary should serve as a useful study aid to understand the critical aspects of cellular respiration for the AP Biology exam.