Which of the following best describes the primary function of glycolysis?

• A. Convert glucose into pyruvate
• B. Produce ATP through oxidative phosphorylation
• C. Synthesize glucose from non-carbohydrate precursors
• D. Store energy in fat cells

Answer: (A)

The primary function of glycolysis is accurately described as converting glucose into pyruvate. This process occurs in the cytoplasm of the cell and is the first step in the breakdown of glucose to extract energy for cellular metabolism. Glycolysis involves a series of enzymatic reactions that ultimately transform one molecule of glucose, a six-carbon sugar, into two molecules of pyruvate, which are three-carbon compounds.

During glycolysis, a net gain of two ATP molecules is produced through substrate-level phosphorylation, as well as the reduction of NAD+ to NADH, which carries high-energy electrons to the electron transport chain for further ATP generation. This process does not depend on oxygen and can occur both aerobically and anaerobically, making it a crucial pathway for energy production in various cellular contexts.

The other options focus on processes that are either part of different metabolic pathways or serve different primary functions. For instance, producing ATP through oxidative phosphorylation refers to a mitochondrial process that requires oxygen and is part of aerobic respiration, while synthesizing glucose from non-carbohydrate precursors refers to gluconeogenesis, which is the reverse of glycolysis. Lastly, storing energy in fat cells relates to lipogenesis, the process of converting excess glucose into fatty acids, rather than