There are different electron carrier carriers in the mitochondria that helps in transferring electron in the Electron Transport Chain.
There are different reactions like Kreb's Cycle and others going in the mitochondrial matrix. These reactions synthesize different reduced proton like NADH₂ and FADH₂. These reduced carriers then go to the inner mitochondrial membrane where there are different electron carriers - four in types namely complex 1,2, 3,and 4 respectively. NADH₂ goes to complex 1 and release the Hydrogen and gets back to NAD and FADH₂ goes to complex 2 and release Hydrogen and gets back to FAD.
The electron that is released to the complex 1 goes to complex 2 and then to Q complex. Then it goes to complex 3 and 4 respectively where the final electron is taken by the oxygen atom to produce oxide ion.
