Topic 12 continued: one of the products of glycolysis is pyruvate. Under normal oxidative conditions pyruvate goes on to be oxidized in the mitochondrion (topic 13) When oxygen is absent, we need some way to regenerate nad+ so glycolysis can continue = fermentation: fermentation. Glycolysis consumes nad+ converts glucose to pyruvate nad+ must be regenerated. Fermentation: pathway that produces atp with no net oxidation of carbon. Electrically neutral there"s no electron input or output, but we"re still making atp. When o2 is present, this is done by the electron transport chain (topic 14) When o2 is absent, other reactions regenerate nad: strategy 1: formation of lactate. Glucose pyruvate reduced to lactate while nadh oxidized to nad+ This nad+ goes back into glycolysis and fuels that reaction. Net reaction: glucose + 2 adp + 2 pi 2 lactate + 2 atp: strategy 2: formation of ethanol.