Which metabolic pathway is primarily used to extract energy from glucose?

The primary metabolic pathway used to extract energy from glucose is glycolysis. This process takes place in the cytoplasm of the cell and begins with the conversion of glucose, a six-carbon sugar, into pyruvate, resulting in the production of a small amount of ATP, which is the energy currency of the cell. Glycolysis is an anaerobic process, meaning it can occur in the absence of oxygen, and it consists of a series of enzymatic reactions leading to the breakdown of glucose.

Following glycolysis, if oxygen is present, pyruvate can proceed to the Krebs cycle (also known as the citric acid cycle or TCA cycle) in the mitochondria, where further energy extraction occurs. However, glycolysis is the initial step that specifically focuses on glucose as a substrate for energy production, making it the correct answer in the context of the question.

In contrast, pathways like fatty acid synthesis and amino acid catabolism do not primarily utilize glucose for energy extraction; instead, they involve the synthesis of fats and the breakdown of amino acids, respectively. Thus, they are not the main metabolic pathways that directly extract energy from glucose.