Cellular Respiration Unit 3: Energize Your Life Chapter 9

Chemical Energy from Food Cells have to convert food into chemical energy. Cells have to convert food into chemical energy. Cellular respiration Cellular respiration releases energy by breaking down food molecules in the presence of oxygen. releases energy by breaking down food molecules in the presence of oxygen. This occurs in the mitochondria. This occurs in the mitochondria.

Cellular Respiration Equation: Equation: 6O 2 + C 6 H 12 O 6  6CO 2 + 6H 2 O + E There are 3 stages of cellular respiration: There are 3 stages of cellular respiration: Glycolysis Glycolysis The Krebs Cycle The Krebs Cycle Electron Transport Chain Electron Transport Chain

Glycolysis 1 molecule of glucose (C 6 H 12 O 6 ) is broken in half into 2 molecules of pyruvic acid. 1 molecule of glucose (C 6 H 12 O 6 ) is broken in half into 2 molecules of pyruvic acid. Does NOT require oxygen. Does NOT require oxygen. Occurs in the cytoplasm. Occurs in the cytoplasm. NAD + is an electron carrier that makes ATP. NAD + is an electron carrier that makes ATP. Glycolysis = net gain of 2 ATP Glycolysis = net gain of 2 ATP

If Oxygen Is NOT Present… After glycolysis, the cell goes into Fermentation. After glycolysis, the cell goes into Fermentation. Fermentation releases energy from food in anaerobic (without oxygen) conditions. Fermentation releases energy from food in anaerobic (without oxygen) conditions. 2 Types: alcoholic fermentation lactic acid fermentation 2 Types: alcoholic fermentation lactic acid fermentation

If Oxygen Is Present… O 2 is present after glycolysis = Krebs Cycle O 2 is present after glycolysis = Krebs Cycle Pyruvic acid (produced by glycolysis) is broken down into CO 2 Pyruvic acid (produced by glycolysis) is broken down into CO 2 Krebs Cycle occurs in the mitochondria Krebs Cycle occurs in the mitochondria

Products of the Krebs Cycle From one molecule of pyruvic acid From one molecule of pyruvic acid 3 molecules of CO 2 3 molecules of CO 2 4 NADH (electron carrier) 4 NADH (electron carrier) 1 FADH 2 (electron carrier) 1 FADH 2 (electron carrier) 1 molecule ATP 1 molecule ATP 2 molecules total of pyruvic acid are broken down 2 molecules total of pyruvic acid are broken down

Electron Transport Chain Electrons are passed from NADH and FADH 2 (produced in Krebs) through the electron transport chain. Electrons are passed from NADH and FADH 2 (produced in Krebs) through the electron transport chain. ETC uses these electrons to convert ADP into ATP. ETC uses these electrons to convert ADP into ATP. Oxygen is necessary to rid the wastes produced. Oxygen is necessary to rid the wastes produced.

Electron Transport Chain Each pair of electrons passed down the ETC provides enough energy to convert 3 ADP into 3 ATP. Each pair of electrons passed down the ETC provides enough energy to convert 3 ADP into 3 ATP. From the Krebs Cycle From the Krebs Cycle 8 NADH produce 24 ATP 8 NADH produce 24 ATP 2 FADH 2 produce 4 ATP 2 FADH 2 produce 4 ATP 2 NADH from glycolysis produce 4 ATP 2 NADH from glycolysis produce 4 ATP

End Results The complete breakdown of glucose through cellular respiration (including glycolysis) results in the production of 36 ATP molecules. The complete breakdown of glucose through cellular respiration (including glycolysis) results in the production of 36 ATP molecules. Glycolysis = 2 ATP Glycolysis = 2 ATP Krebs Cycle = 2 ATP Krebs Cycle = 2 ATP Electron Transport Chain = 32 ATP Electron Transport Chain = 32 ATP