What is the primary function of glycolysis in cellular respiration?

Glycolysis is a critical metabolic pathway in cellular respiration that primarily functions to break down glucose into pyruvic acid. This ten-step process occurs in the cytoplasm of the cell and does not require oxygen, making it an anaerobic pathway.

During glycolysis, one glucose molecule (a six-carbon sugar) is phosphorylated and ultimately converted into two molecules of pyruvic acid (each having three carbons). This conversion releases energy that is captured in the form of ATP and NADH. Specifically, glycolysis nets two molecules of ATP directly through substrate-level phosphorylation and produces two NADH molecules, which carry electrons to later stages of cellular respiration.

In the context of cellular respiration, the conversion of glucose into pyruvic acid is crucial, as it serves as the initial step for further energy extraction in processes such as the Krebs cycle and oxidative phosphorylation if oxygen is present. Thus, the primary function of glycolysis aligns perfectly with breaking down glucose to produce pyruvic acid.