▁the ▁o xygen ▁concentration ▁is ▁low , ▁the ▁product ▁of ▁g ly col ysis , ▁py ru v ate , ▁is ▁turned ▁into ▁eth an ol ▁and ▁carbon ▁dio x ide , ▁and ▁the ▁energy ▁production ▁efficiency ▁is ▁low ▁( 2 ▁mol es ▁of ▁ATP ▁per ▁mole ▁of ▁gl uc ose ). ▁If ▁the ▁o xygen ▁concentration ▁grows , ▁py ru v ate ▁is ▁converted ▁to ▁ac et yl ▁Co A ▁that ▁can ▁be ▁used ▁in ▁the ▁cit ric ▁acid ▁cycle , ▁which ▁increases ▁the ▁efficiency ▁to ▁ 3 1 ▁or ▁ 2 9 . 5 ▁mol es ▁of ▁ATP ▁per ▁mole ▁of ▁gl uc ose ▁( it ▁depends ▁on ▁which ▁sh utt le ▁is ▁used ▁for ▁reducing ▁the ▁reducing ▁equivalent , ▁N AD H , ▁that ▁is ▁formed ▁in ▁the ▁c yt os ol ). ▁Therefore , ▁about ▁ 1 5 ▁times ▁as ▁much ▁gl uc ose ▁must ▁be ▁consum ed ▁an a er ob ically ▁as ▁aer ob ically ▁to ▁yield ▁the ▁same ▁amount ▁of ▁ATP . ▁ ▁Under ▁an a er ob ic ▁conditions , ▁the ▁rate ▁of ▁gl uc ose ▁met abol ism ▁is ▁faster , ▁but ▁the ▁amount ▁of ▁ATP ▁produced ▁( as ▁already ▁mentioned ) ▁is ▁smaller . ▁When ▁exposed ▁to ▁aer ob ic ▁conditions , ▁the ▁ATP ▁and ▁Cit rate ▁production ▁increases ▁and ▁the ▁rate ▁of ▁g ly col ysis ▁slow s , ▁because ▁the ▁ATP ▁and ▁cit rate ▁produced ▁act ▁as ▁al loster ic ▁in hib itors ▁for ▁ph osph of ruct ok in ase