NAD in glycolysis in Aerobic RespirationWatch
Actually i think i may have worked this out myself. Is it that Glycolysis only needs to occur once then then the krebs cycle can continue over and over in a cycle, without needing glycolysis to occur again?
In response to your original question, NAD must ALWAYS be replenished - cells never make more NAD so they must re-oxidise what they have or glycolysis can't continue as there will be nowhere for the electrons to go. The electron transport chain re-oxidises NAD in aerobic respiration because the electrons are given up by NAD to drive proton flow, right? And loss of electrons = oxidised etc etc.