Final answer:
During glycolysis, glucose is broken down into two pyruvic acid molecules. 2 ATP are used but 4 ATP are produced, and 2 NAD molecules are charged up to 2 NADH molecules.
Step-by-step explanation:
Glycolysis is the first step in cellular respiration, where glucose is converted into two pyruvic acid molecules. During glycolysis, 2 ATP molecules are used, but 4 ATP molecules are produced. Additionally, 2 NAD molecules are charged up to 2 NADH molecules. However, it is important to note that the production of ATP during glycolysis is zero, as the two ATP molecules are used to transport the NADH into the mitochondria for further ATP production.