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Cellular Respiration. Chapter 9. Chemical Energy and Food. Living things get the energy they need from food. The process of releasing the energy stored in food is cellular respiration . Overview of Cellular Respiration. In the presence of oxygen, aerobic respiration takes place.
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Cellular Respiration Chapter 9
Chemical Energy and Food • Living things get the energy they need from food. • The process of releasing the energy stored in food is cellular respiration.
Overview of Cellular Respiration • In the presence of oxygen, aerobic respiration takes place. • This produces 36 ATP per molecule of glucose. • In the absence of oxygen, anaerobic respiration (fermentation) takes place. • This produces 2 ATP per molecule of glucose.
Chemical Pathways Section 9-1 Glucose Krebs cycle Electrontransport Glycolysis Alcohol or lactic acid Fermentation (without oxygen)
Glycolysis • Both aerobic and anaerobic respiration begin with a process known as glycolysis. • This means “glucose -splitting” • This takes place in the cytoplasm.
Glycolysis Section 9-1 Glucose 2 Pyruvic acid To the electron transport chain
Glycolysis Section 9-1 Glucose 2 Pyruvic acid To the electron transport chain
Glycolysis Section 9-1 Glucose 2 Pyruvic acid To the electron transport chain
Glycolysis • If oxygen is available, the pyruvic acid molecules will be broken down further to release more energy. • If oxygen is unavailable, the pyruvic acid molecules will be converted to a waste product with no further release of energy (fermentation).
Chemical Pathways Section 9-1 Glucose Krebs cycle Electrontransport Glycolysis Alcohol or lactic acid Fermentation (without oxygen)
Fermentation • Also known as anaerobic respiration. • Two types: • Alcoholic fermentation – in yeasts • Pyruvic acid is converted to alcohol and carbon dioxide. • Lactic acid fermentation – in bacteria and muscle cells • Pyruvic acid is converted to lactic acid.
Lactic Acid Fermentation Section 9-1 Lactic acid Glucose Pyruvic acid
Aerobic Respiration • 6O2 + C6H12O6 6CO2 + 6H2O + 36 ATP • Oxygen + glucose carbon dioxide + water + energy
Mitochondrial Reactions Mitochondrion Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Electron Transport Chain Krebs Cycle Glycolysis Mitochondrion Cytoplasm
Flowchart Section 9-2 Aerobic Cellular Respiration Glucose(C6H1206) + Oxygen(02) Glycolysis KrebsCycle ElectronTransportChain Carbon Dioxide (CO2) + Water (H2O)
Aerobic Respiration • In the presence of oxygen, pyruvic acid is further broken down to release additional energy. • This takes place in the mitochondria. • There are two steps: • The Krebs Cycle • The electron transport chain
The Krebs Cycle • Also known as the citric acid cycle. • Pyruvic acid (from glycolysis) is broken down into carbon dioxide. • High energy electrons are captured by NAD and FAD and brought to the electron transport chain. • Net gain of 2 ATP from this cycle.
The Krebs Cycle Section 9-2 Citric Acid Production Mitochondrion
Electron Transport Chain • NADH and FADH2 drop off high energy electrons. • These pass through a series of reactions located on the inner membrane that produce ATP. • Oxygen combines with hydrogen to make water. • Net gain of ATP = 32
Electron Transport Chain Section 9-2 Electron Transport Hydrogen Ion Movement Channel Mitochondrion Intermembrane Space ATP synthase Inner Membrane Matrix ATP Production
ATP totals • Glycolysis – 2 • Krebs Cycle – 2 • Electron Transport Chain – 32 • Net: from one glucose molecule = 36 ATP