The cristae have an electron transport mechanism (inner membrane infoldings of mitochondria). It is composed of cytochromes and co-enzymes, which function as carrier and transfer molecules. These molecules take electrons with high energy and transfer them on to the next molecule in the system. The energy of electrons is used to pump protons into the outer compartment of mitochondria at proton-pumping sites. ATP synthase uses these protons to create energy molecules known as ATPs. This entire process is known as a 'oxidation-reduction reaction.'