Final answer:
The amount of ATP produced can be broken down by pathways: Glycolysis yields 2 ATP per glucose, the conversion of pyruvate to acetyl CoA produces around 6 ATP, the Krebs cycle potentially contributes 22 ATP, and the Electron Transport Chain (ETC) generates the majority with about 34 ATP.
Step-by-step explanation:
To answer how much ATP is produced by each enzyme or each pathway in cellular respiration, we have to consider several stages, including glycolysis, the transition from pyruvate to acetyl CoA, the Krebs cycle, and the electron transport chain (ETC).
Glycolysis
During glycolysis, a net total of 2 ATPs are produced per glucose molecule.
Transition Stage
Converting each pyruvate into acetyl CoA yields 2 NADH, which are worth approximately 3 ATP each when they donate their electrons to the ETC, totaling around 6 ATP for both pyruvate molecules.
Krebs Cycle
The Krebs cycle generates a large amount of reduced coenzymes (NADH and FADH₂) per glucose molecule: 6 NADH and 2 FADH₂, which equals to a potential of about 18 ATP from NADH (3 ATP per NADH) and 4 ATP from FADH₂ (2 ATP per FADH₂).
Electron Transport Chain (ETC)
In the ETC, the NADH and FADH₂ from the earlier stages contribute their electrons to produce ATP.
The 10 NADH produce roughly 30 ATP (considering the 2 from glycolysis in the cytoplasm may provide a little less, with some accounting for a NADH transport cost) and the 2 FADH₂ provide approximately 4 ATP. So, the ETC is responsible for the bulk of the ATP produced, around 34 ATP.
Pathway Producing the Most ATP: The electron transport chain is the pathway that produces the most ATP molecules due to its utilization of the high energy electrons carried by NADH and FADH₂.
The variation in the number of ATP molecules produced can be attributed to differences in conditions and transport costs, particularly the transport of NADH produced in glycolysis into the mitochondria.
Additionally, steps like the conversion of pyruvate into acetyl CoA and the end product inhibition mechanism epitomized by enzymes like phosphofructokinase play a significant role in regulation and efficiency of ATP production.