Final answer:
The Krebs cycle, taking place in the mitochondria, produces the most NADH during cellular respiration with 6 NADH molecules generated per glucose molecule; a total of 10 NADH are produced in the mitochondria which contribute to around 30 ATP through the electron transport chain.
Step-by-step explanation:
The part of cellular respiration that produces the most NADH is the Krebs cycle (also known as the citric acid cycle), which occurs in the mitochondria. During the Krebs cycle, for every molecule of glucose, 6 NADH molecules are produced. However, it is important to note that glycolysis and the conversion of pyruvate to acetyl CoA produce 2 NADH each before the Krebs cycle begins, totaling to 10 NADH molecules produced in the mitochondria.
Each of these NADH molecules are then used in the electron transport chain (ETC) to produce ATP. In the ETC, about three ATP are produced for every oxidized NADH, amounting to approximately 30 ATP from NADH generated by one molecule of glucose after accounting for the transport cost of NADH from glycolysis into the mitochondria.