metabolic cycle

A metabolic pathway is a series of chemical reactions in a cell, each catalyzed by an enzyme. When the end product of a pathway is also its starting reactant, it's called a metabolic cycle. These cycles can be catabolic (energy-releasing, breaking down complex molecules) or anabolic (energy-consuming, building molecules).

Key cycles include glycolysis, which breaks down glucose into malate, and the tricarboxylic acid (TCA) cycle, also known as the Krebs cycle. These processes generate energy, primarily in the form of adenosine triphosphate (ATP), which fuels cellular activities. Defects in these pathways can lead to metabolic diseases.