How much total energy is produced by glycolysis?

Glycolysis is a crucial metabolic pathway that converts glucose into pyruvate, generating energy in the process. During glycolysis, a total of four ATP molecules are produced through substrate-level phosphorylation. However, two of these ATP molecules are consumed during the initial steps of glucose activation, resulting in a net production of two ATP.

In addition to ATP, glycolysis results in the generation of two NADH molecules. This occurs when glyceraldehyde-3-phosphate is oxidized, and NAD+ is reduced to form NADH. The NADH produced can subsequently be used in aerobic or anaerobic respiration to generate additional ATP through oxidative phosphorylation.

The overall energy yield from glycolysis is thus represented as 2 NADH and a net gain of 2 ATP, making that combination the correct and comprehensive answer for total energy yield from this pathway.