1. Fuel Sources:
* Glucose: This is the primary fuel source for most cells, but other sugars, fatty acids, and amino acids can also be used.
* Pyruvate: This is a product of glycolysis, which breaks down glucose in the cytoplasm.
2. Electron Carriers:
* NADH and FADH2: These molecules are produced during the breakdown of fuels in the cytoplasm (glycolysis) and within the mitochondria (Krebs cycle). They carry high-energy electrons.
3. Electron Transport Chain (ETC):
* This is a series of protein complexes embedded in the inner mitochondrial membrane. Electrons from NADH and FADH2 pass through the ETC, releasing energy along the way.
4. Proton Gradient:
* The energy released by the ETC is used to pump protons (H+) from the mitochondrial matrix across the inner membrane into the intermembrane space. This creates a proton gradient, where there is a higher concentration of protons in the intermembrane space.
5. ATP Synthase:
* This enzyme is also embedded in the inner mitochondrial membrane. It acts like a turbine, using the proton gradient to drive the synthesis of ATP from ADP and inorganic phosphate (Pi).
Here's a simplified breakdown:
1. Fuel sources enter the mitochondria and are broken down to release electrons.
2. Electron carriers NADH and FADH2 pick up these high-energy electrons.
3. The ETC uses the energy from the electrons to pump protons across the membrane.
4. The proton gradient provides the energy for ATP synthase to generate ATP.
In essence, the mitochondria takes in fuel, electrons, and oxygen to generate ATP, the cell's energy currency, using a complex process of electron transport and proton gradients.
