The electron transport chain and oxidative phosphorylation

Overview

Ultimate hydrogen acceptor in aerobic respiration, why reduced flavoprotein yields less ATP than reduced NAD and oxidative phosphorylation.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Where is the electron transport chain found in the mitochondrion?

   Model answer

   The chain is a series of carrier molecules embedded in the inner mitochondrial membrane, which is folded into cristae.

2. 2

   Name the carriers of the electron transport chain in the order electrons pass along them.

   Model answer

   Hydrogen and its electrons pass from reduced NAD to flavoprotein, then to coenzyme Q, then along the cytochromes and finally to oxygen.

3. 3

   Why are the carriers of the electron transport chain arranged in the order they are?

   Model answer

   Each carrier in turn sits at a lower energy level than the one before, so electrons release a little energy at every transfer rather than all of it at once.

4. 4

   What is the ultimate hydrogen acceptor in aerobic respiration?

   Model answer

   Oxygen is the ultimate hydrogen acceptor, which is why the pathway cannot run without it.

5. 5

   Write an equation for the reaction of oxygen at the end of the electron transport chain.

   Model answer

   The reaction is ½O₂ + 2H⁺ + 2e⁻ → H₂O.

6. 6

   How many molecules of ATP are generated for each pair of hydrogen atoms entering the chain at reduced NAD?

   Model answer

   Each pair of hydrogen atoms entering at reduced NAD yields three molecules of ATP.

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