Answer:
This is by co enzymes NADH and FADH2(adenine dinucleotide hydrogen and falvin adeninedinucleotide hydrogen. They are the co-enzymes that convey (electrons in )hydrogen atoms from the Kreb's cycle to the matrix of the  mitochondria.They are not enzymes,but rather, enhances the work of enzymes.
These co enzymes are oxidized by the loss of hydrogen atoms.The hydrogen spits into electrons and protons in the matrix.The protons is pumped into the intramembranes by the proton motive force produced from the  electron transport chains,and returned to the  matrix, to generate electrochemical gradient needed for  energy to be used by ATPase synthase for ATPs production
Explanation:
