The electron transport chain

• This chain contains complexes known as cytochromes w/ single-Fe³⁺-ion heme groups

• The Fe³⁺ ion in a cytochrome accepts a reduced coenzyme’s electrons so it can be reduced to Fe²⁺ itself

• The energy released from the electrons here is used for pumping protons into the inter-membrane space

Steps in oxidative phosphorylation

1. Firstly the reduced NAD + FAD coenzymes get oxidized via their release of hydrogen atoms (if this step were to be skipped along with glycolysis no triose phosphate → pyruvate conversions would occur)

2. The hydrogen atoms released by the reduced coenzymes then split to produce hydrogen protons and free electrons

3. The electrons produced then move along the electron transport chain where the cytochromes’ Fe³⁺ ions get reduced themselves by accepting those electrons

4. The energy released from the electron transport chain then gets used for the active pumping of protons into the mitochondrial inter-membrane space

5. The protons pumped into that space then accumulate there to create a proton gradient w/ chemiosmotic potential that can be sourced for potential energy

6. These protons then diffuse down the proton channels of ATP synthase molecules in the inner mitochondrial membrane into the matrix

7. The protons flowing down the proton channels then join with the ADP + P_i molecules in the matrix via catalyzed phosphorylation reactions in a rotating manner