1. Glycolysis:
* Location: Cytoplasm
* Process: Glucose is broken down into two molecules of pyruvate.
* Energy yield: 2 ATP molecules and 2 NADH molecules (electron carriers).
2. Pyruvate Oxidation:
* Location: Mitochondria
* Process: Pyruvate is converted into acetyl-CoA, a molecule that enters the citric acid cycle.
* Energy yield: 1 NADH molecule per pyruvate molecule.
3. Citric Acid Cycle (Krebs Cycle):
* Location: Mitochondria
* Process: Acetyl-CoA enters the citric acid cycle, a series of reactions that produce electron carriers and carbon dioxide.
* Energy yield: 3 NADH molecules, 1 FADH2 molecule (another electron carrier), and 1 ATP molecule per acetyl-CoA molecule.
4. Oxidative Phosphorylation (Electron Transport Chain):
* Location: Mitochondria
* Process: NADH and FADH2 molecules donate their electrons to a series of protein complexes in the electron transport chain. This electron flow drives the pumping of protons across the mitochondrial membrane, creating a proton gradient. The energy stored in this gradient is used by ATP synthase to generate ATP.
* Energy yield: Approximately 28-34 ATP molecules per glucose molecule.
Overall, the complete breakdown of one glucose molecule through cellular respiration yields approximately 38 ATP molecules. This energy is used to power various cellular processes, including muscle contraction, active transport, and protein synthesis.
Key points to remember:
* Cellular respiration is an aerobic process, meaning it requires oxygen.
* The majority of ATP is produced during oxidative phosphorylation.
* Electron carriers (NADH and FADH2) play a crucial role in transferring electrons and generating a proton gradient for ATP synthesis.
In summary, glucose is transformed into ATP through a series of interconnected reactions that involve glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation. This process is essential for life as it provides the energy required for cellular functions.
