Fermentation

ATP - Adenosine TriPhosphate

ATP is “spring-loaded” The phosphates have a negative charge –repel each other This means potential energy is stored in the bonds

Aerobic Respiration The oxygen is electronegative and pulls the electrons down the ETC Without it, no oxidative phosphorylation happens

NAD + regeneration To keep cycling glycolysis, we need NAD + to be in sufficient supply This is done by transferring the electrons from NADH back to pyruvate

Fermentation Glycolysis still happens – NAD + oxidizes glucose to 2 pyruvate No ETC, so no 32 ATPs Fermentation cycles glycolysis again and again

Two types Alcohol Fermentation Pyruvate is converted to ethyl alcohol (ethanol) Yeast – used for bread, wine, beer Lactic Acid Fermentation Pyruvate is converted to lactate (ionized form of lactic acid) Fungi and bacteria – used for cheese and yogurt Humans – in our muscle cells

Which is better? Aerobic Respiration 19 times as much ATP 38 ATP per glucose 38 x 7.3 kcal/mol = kcal Fermentation 2 ATP per glucose 2 x 7.3 kcal/mol = 14.6 kcal

Two types of anaerobes Obligate anaerobes Can only do fermentation or anaerobic respiration Can’t survive in the presence of oxygen Facultative anaerobes Can do both Our muscle cells behave this way

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