Answer: The process of generating energy from glucose occurs through cellular respiration, specifically during glycolysis, the citric acid cycle, and oxidative phosphorylation. Let's break down the energy production from glucose:
Explanation: Glycolysis: Glycolysis is the initial step in cellular respiration where one molecule of glucose (a 6-carbon compound) is converted into two molecules of pyruvate (a 3-carbon compound). During glycolysis, a small amount of ATP is consumed (2 ATP molecules are used) to activate glucose and split it into two pyruvate molecules. However, glycolysis also produces a net gain of 2 ATP molecules and 2 NADH molecules (which can be later used to produce more ATP).
Net ATP Produced in Glycolysis: 2 ATP (produced) - 2 ATP (used) = 0 ATP
Citric Acid Cycle (Krebs Cycle): Each pyruvate molecule is further broken down into carbon dioxide in the citric acid cycle. Although this process doesn't produce a large amount of ATP directly, it generates high-energy electron carriers (NADH and FADH2) that will be used in the next step.
Oxidative Phosphorylation (Electron Transport Chain and ATP Synthase): The high-energy electrons carried by NADH and FADH2 are transferred through the electron transport chain, generating a proton gradient across the inner mitochondrial membrane. The flow of protons back into the mitochondria through ATP synthase results in the production of ATP through a process called chemiosmosis.
The exact number of ATP molecules produced from the energy generated by NADH and FADH2 can vary, but a common estimate is about 2.5 to 3 ATP molecules per NADH and 1.5 to 2 ATP molecules per FADH2.
Considering that glycolysis produces 2 NADH molecules (which can generate approximately 5 ATP molecules) and 2 ATP molecules directly, the overall ATP production from glycolysis, citric acid cycle, and oxidative phosphorylation is approximately 29 to 30 ATP molecules per glucose molecule.