How Cellular Respiration Powers Your Cells

Cellular respiration begins with glucose, your cells' primary fuel source.Glycolysis occurs in the cell's cytoplasm, where complex glucose molecules are broken down.The process begins with an investment of energy - two ATP molecules are used to start the reaction.Through a series of chemical reactions, the glucose molecule is split into two pyruvate molecules.This process generates a net gain of two ATP molecules and two NADH molecules.Importantly, this initial stage of cellular respiration doesn't require oxygen, making it an anaerobic process.The pyruvate molecules produced here will continue to the next phase of cellular respiration.Inside the mitochondria, pyruvate molecules are transformed into acetyl-CoA, which enters the citric acid cycle.The citric acid cycle, also known as the Krebs cycle, is a series of chemical reactions that break down acetyl-CoA to generate energy-carrying molecules.As molecules move through the cycle, they undergo a series of transformations, each step producing specific products.At several points in the cycle, NADH molecules are produced, which will be used later for energy production.The cycle also produces FADH₂, another energy-carrying molecule.Carbon dioxide is released as a waste product at two points in the cycle.For each glucose molecule that enters cellular respiration, the citric acid cycle runs twice, producing these important molecules.These energy-carrying molecules, NADH and FADH₂, will now move to the electron transport chain for the final phase of cellular respiration.The electron transport chain is located in the inner membrane of the mitochondria.NADH delivers electrons to Complex One, starting the electron transport process.As electrons move through the complexes, protons are pumped across the membrane, creating a gradient.The proton gradient drives ATP synthase like a turbine, powering the production of ATP from ADP and phosphate.Oxygen serves as the final electron acceptor, combining with protons to form water.This process is highly efficient, with each NADH molecule helping to produce two to three ATP molecules.