Explain the differences between aerobic and anerobic respiration in terms of the roles of co-enzymes

During aerobic respiration, NAD and FAD collect protons and electrons from respiratory substrates. These electrons can be released into the transport chain of the mitochondrial matrix because oxygen is present in aerobic respiration so oxygen can accept electrons after they travel through the chain. The protons can be released and move across the inner membrane by active transport and then back through ATP synthase, to move on to oxygen to produce water (oxidative phosphorylation) and producing large amounts of ATP in the process. However during anerobic respiration, oxygen is not present so protons and electrons can’t be removed from the cell (as water). This means that oxidative phosphorylation cannot occur as a build up of protons and electrons would be lethal to the cell.The coenzyme NAD is still used to oxidise triose phosphate, producing a net of 2 ATP but converting all the cells NAD into NADH. NAD must be regenerated in order to continue oxidising triose phosphate to continue making ATP as the cell will otherwise use up all NAD to create NADH and be unable to generate ATP anerobically. NADH must now be regenerated some other way instead of during oxidative phosphorylation. So NADH reduces pyruvate, producing lactic acid and regenerating NAD, allowing triose phosphate to continue being oxidised inorder to produce ATP without oxygen.