Final answer:
During glycolysis, two NADH molecules are produced from the breakdown of a single molecule of glucose. These NADH molecules are important for the subsequent production of ATP in the electron transport chain.
Step-by-step explanation:
Glycolysis is a biochemical pathway that breaks down glucose into pyruvate, yielding ATP and NADH. During glycolysis, each molecule of glucose is converted to two molecules of pyruvate, and in the process, a total of two molecules of NADH are produced. Specifically, these two NADH molecules are generated in the step catalyzed by glyceraldehyde-3-phosphate dehydrogenase.
The question asks for the number of NADH produced by glycolysis. Given the details of the glycolytic pathway, the final answer to the student's question is two molecules of NADH. This is important because these NADH molecules will be subsequently used in the electron transport chain (ETC) to produce ATP. The electrons from these NADH molecules enter the ETC, where they are passed down a series of proteins, ultimately leading to the production of ATP. While each NADH would traditionally yield three ATPs when oxidized in the ETC, the actual ATP yield can differ depending on the shuttle system used to transport NADH from the cytosol into the mitochondria.
Therefore, the number of NADH molecules produced directly from glycolysis, which occurs in the cytosol, is two. This does not account for the additional ATP that might be produced from these molecules in the ETC, nor does it factor in the NADH that is produced in later stages of cellular respiration, such as the conversion of pyruvate to acetyl-CoA or the citric acid cycle.