During glycolysis, what is broken down to release energy?

During glycolysis, glucose is the molecule that is broken down to release energy. This process occurs in the cytoplasm of the cell and involves a series of enzymatic reactions that convert one molecule of glucose, a six-carbon sugar, into two molecules of pyruvate, each containing three carbons. As glucose is processed during glycolysis, energy in the form of ATP (adenosine triphosphate) is produced, along with reduced coenzymes like NADH.

The breakdown of glucose is essential because it not only provides the energy currency (ATP) that cells require for various functions but also generates pyruvate, which can enter further pathways like the Krebs cycle if oxygen is present. This makes glycolysis a critical first step in both aerobic and anaerobic respiration processes. Other molecules mentioned, such as fatty acids, carbon dioxide, and amino acids, do not undergo glycolysis but may be involved in different metabolic pathways for energy production and utilization.