How much ATP does NADH produce

If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

The electron transport chain is located on the inner membrane of the mitochondria, as shown below.

Figure 6.261 The pathways involved in aerobic respiration1

The electron transport chain contains a number of electron carriers. These carriers take the electrons from NADH and FADH2, pass them down the chain of complexes and electron carriers, and ultimately produce ATP. More specifically, the electron transport chain takes the energy from the electrons on NADH and FADH2 to pump protons (H+) into the intermembrane space. This creates a proton gradient between the intermembrane space (high) and the matrix (low) of the mitochondria. ATP synthase uses the energy from this gradient to synthesize ATP. Oxygen is required for this process because it serves as the final electron acceptor, forming water. Collectively this process is known as oxidative phosphorylation. The following figure and animation do a nice job of illustrating how the electron transport chain functions.

Figure 6.262 Location of the electron transport chain in the mitochondria2

2.5 ATP/NADH and 1.5 ATP/FADH2 are produced in the electron transport chain. Some  resources will say 3 ATP/NADH and 2 ATP/FADH2, but these values are generally less accepted now.

For one molecule of glucose, the preceding pathways produce:

Glycolysis:   2 NADH

Transition Reaction:  2 NADH

Citric Acid Cycle:     6 NADH, 2 FADH2

Total 10 NADH, 2 FADH2

Multiply that by the amount of ATP per NADH or FADH2 to yield:

10 NADH  X  2.5 ATP/NADH = 25 ATP

  2 FADH2 X 1.5 ATP/FADH2  =  3 ATP

Total 28 ATP

The first video does a nice job of illustrating and reviewing the electron transport chain. Note that it uses 3 ATP/NADH and 2 ATP/FADH2 so the totals from each cycle are different from those listed above. The second video is a great rap video explaining the steps of glucose oxidation.

References & Links

1. http://en.wikipedia.org/wiki/File:CellRespiration.svg

2. http://en.wikipedia.org/wiki/File:Mitochondrial_electron_transport_chain%E2%80%94Etc4.svg

Link

ETC Animation – http://www.science.smith.edu/departments/Biology/Bio231/etc.html

Videos

Electron Transport Chain – http://www.youtube.com/watch?v=1engJR_XWVU&feature=related

Oxidate it or Love it/Electron to the Next One – http://www.youtube.com/watch?v=VCpNk92uswY&feature=response_watch

8.12: ATP Yield

Cellular respiration produces 30-32 ATP molecules per glucose molecule. Although most of the ATP results from oxidative phosphorylation and the electron transport chain (ETC), 4 ATP are gained beforehand (2 from glycolysis and 2 from the citric acid cycle).

The ETC is embedded in the inner mitochondrial membrane and comprises four main protein complexes and an ATP synthase. NADH and FADH2 pass electrons to these complexes, which in turn pump protons into the intermembrane space. This distribution of protons generates a concentration gradient across the membrane. The gradient drives the production of ATP when protons flow back into the mitochondrial matrix via the ATP synthase.

For every 2 input electrons that NADH passes into complex I, complexes I and III each pump 4 protons and complex IV pumps 2 protons, totaling 10 protons. Complex II is not involved in the electron chain initiated by NADH. FADH2, however, passes 2 electrons to complex II, so a total of 6 protons are pumped per FADH2; 4 protons via complex III and 2 via complex IV.

Four protons are needed to synthesize 1 ATP. Since 10 protons are pumped for every NADH, 1 NADH yields 2.5 (10/4) ATP. Six protons are pumped for every FADH2, so 1 FADH2 yields 1.5 (6/4) ATP.

Cellular respiration produces a maximum of 10 NADH and 2 FADH2 per glucose molecule. Since a single NADH produces 2.5 ATP and a single FADH2 produces 1.5 ATP, it follows that 25 ATP + 3 ATP are produced by oxidative phosphorylation. Four ATP are produced before oxidative phosphorylation, which yields a maximum of 32 ATP per glucose molecule.

Importantly, glycolysis occurs in the cytosol and the ETC is located in the mitochondria (in eukaryotes). The mitochondrial membrane is not permeable to NADH, hence the electrons of the 2 NADH that are produced by glycolysis need to be shuttled into the mitochondria. Once inside the mitochondrion, the electrons may be passed to NAD+ or FAD. Given the different ATP yield depending on the electron carrier, the total yield of cellular respiration is 30 to 32 ATP per glucose molecule.

Suggested Reading

How many ATP are produced from NADH?

Does 1 NADH produce 3 ATP or 2.5 ATP?

How much ATP is produced by Nadph?

Does NADH produce the most ATP?