1. Chemical Energy and Food A calorie is a unit of energy. A calorie is a unit of energy. A calorie is the amount of energy needed to raise the temperature of one gram of water 1 o C. A calorie is the amount of energy needed to raise the temperature of one gram of water 1 o C. 1000 calories = one Calorie (kilocalorie) 1000 calories = one Calorie (kilocalorie)

2. Chemical Energy and Food The process of getting energy from food begins with glycolysis. The process of getting energy from food begins with glycolysis. Glycolysis releases only a small amount of energy. Glycolysis releases only a small amount of energy. If oxygen is present, glycolysis leads to two other pathways that release a lot of energy. If oxygen is present, glycolysis leads to two other pathways that release a lot of energy.

3. Chemical Energy and Food Glycolysis is followed by the Krebs cycle and the electron transport chain. Glycolysis is followed by the Krebs cycle and the electron transport chain. These three steps are known as cellular respiration. These three steps are known as cellular respiration. 60 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O +Energy 60 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O +Energy

4. Glycolysis Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid. Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid. Glycolysis Two high-energy electrons from glucose are moved to a NAD+ molecule and it becomes NADH. Two high-energy electrons from glucose are moved to a NAD+ molecule and it becomes NADH. The energy contained in NADH then moves to the electron transport chain. The energy contained in NADH then moves to the electron transport chain.

5. Fermentation When oxygen is not present, glycolysis is followed by fermentation. When oxygen is not present, glycolysis is followed by fermentation. Fermentation releases energy from food by producing ATP in the absence of oxygen. Fermentation releases energy from food by producing ATP in the absence of oxygen. If a process doesn’t need oxygen it is anaerobic. If a process doesn’t need oxygen it is anaerobic.

6. Fermentation Yeasts and some other microorganisms turn pyruvic acid into alcohol and CO 2. Yeasts and some other microorganisms turn pyruvic acid into alcohol and CO 2. Your body can turn pyruvic acid into lactic acid and NAD+ to keep using energy. Your body can turn pyruvic acid into lactic acid and NAD+ to keep using energy.