Oxidation of food inside cell takes place in mitochondria.

The process of oxidation of food is a vital metabolic process that occurs in living cells to release energy. This energy is necessary for various cellular activities, such as growth, movement, and maintaining homeostasis. The oxidation of food molecules primarily takes place in the organelle called mitochondria.

What are mitochondria?
Mitochondria are double-membraned organelles found in most eukaryotic cells. They are often referred to as the "powerhouses of the cell" due to their role in producing energy in the form of ATP (adenosine triphosphate). Mitochondria have their own genetic material and are believed to have originated from ancient symbiotic relationships between primitive eukaryotic cells and aerobic bacteria.

The process of oxidation in mitochondria:
1. Glycolysis: The oxidation of food molecules begins in the cytoplasm of the cell, where glucose molecules are broken down through a process called glycolysis. During glycolysis, glucose is converted into pyruvate, producing a small amount of ATP.

2. Pyruvate Decarboxylation: The pyruvate molecules produced in glycolysis are transported into the mitochondria. Within the mitochondria, each pyruvate molecule undergoes decarboxylation, resulting in the release of carbon dioxide and the formation of acetyl-CoA.

3. Krebs Cycle (Citric Acid Cycle): The acetyl-CoA molecules enter the Krebs cycle, also known as the citric acid cycle. This cycle takes place in the mitochondrial matrix and involves a series of chemical reactions that further oxidize the acetyl-CoA molecules. During the Krebs cycle, carbon dioxide, ATP, NADH, and FADH2 are produced as byproducts.

4. Electron Transport Chain: The NADH and FADH2 molecules generated in the Krebs cycle carry high-energy electrons. These electrons are transferred to the electron transport chain, which is embedded in the inner mitochondrial membrane. The electron transport chain uses the energy from these electrons to pump protons across the membrane, creating an electrochemical gradient. This gradient drives the production of ATP through a process called oxidative phosphorylation.

5. ATP Production: The final step of oxidation is ATP production. As protons flow back into the mitochondrial matrix through an enzyme called ATP synthase, ATP molecules are synthesized. This process is known as chemiosmosis and is responsible for the majority of ATP production in aerobic organisms.

Overall, the oxidation of food molecules takes place in mitochondria through a series of interconnected metabolic pathways. This process efficiently converts the chemical energy stored in food into a usable form of energy (ATP) that powers cellular functions.