Electron Transport Phosphorylation

occurs in the membranes of the mitochondria (cristae).

• NADH and FADH₂ give up their electrons to transport (enzyme) systems embedded in the mitochondrial inner membrane.
• H+ are released into the outer compartment of the mitochondrion.
• As H+ flow back into the inner compartment, ATP synthases form ATP from ADP and unbound phosphate.
• Oxygen is the terminal electron acceptor. It joins with the "spent" electrons and H+ to yield water.

The generation of concentration gradients across the membranes of mitochondria is known as the chemiosmotic theory of ATP production.

This animation (Audio - Important) describes electron transport.

This animation (Audio - Important) describes how electron transport takes place in the mitochondrion.

How many ATP are formed at each step of the way:

• Glycolysis yields two ATP
• Krebs Cycle yields two ATP
• Electron transport yields thirty-two ATP
• For a grand total of thirty-six ATP per glucose molecule .

Actually, the yield of ATP can vary somewhat because there are other pathways that can interact with the three pathways that we have been discussing and remove intermediates along the way.

This figure is a good overview of ATP yield and the interaction of glycolysis, the Krebs Cycle, and the Electron Transport Chain. When energy is transferred from glucose to ATP, the efficiency is about 40%. (Is that because of the first or second law of thermodynamics?)

These animations (Audio - Important) describes ATP yield
ATP yield version 1.
ATP yield version 2.
ATP yield version 3.

REVIEW: When glucose is used as the energy source, the largest amount of ATP is produced in
Answer electron transport phosphorylation.