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Complementary Cycles. Food Stores Chemical Energy. Chemical Energy is a form of potential energy due to the arrangement of the atoms within the molecules. Food Stores Chemical Energy. Accessing the Energy in Food.
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Food Stores Chemical Energy • Chemical Energy is a form of potential energy due to the arrangement of the atoms within the molecules.
Accessing the Energy in Food • Cellular Respiration – a chemical process that uses oxygen to convert the chemical energy in food into ATP.
Accessing the Energy in Food Cellular Respiration - Aerobic Respiration: requires oxygen Anaerobic Respiration: without oxygen (fermentation)
Cellular Respiration Location – Mitochondria
Cellular Respiration – The Big Picture http://www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html
Cellular Respiration • Stage 1: Glycolysis • Takes place in cytoplasm • “Splitting Sugar” • Glucose splits into 2 Pyruvic Acid molecules. • 2 Molecules of ATP are spent, but 4 are made. (Net of 2 ATP molecules made) • NAD+ picks up e- and brings to ETC. To e- Transport Pyruvic Acid
Cellular Respiration • Stage 2: Krebs Cycle • Takes place in mitochondrial matrix. • Pyruvic Acid molecules lose molecules of CO2 and becomes a new substance (citric acid). • ATP and electron carriers pick up most of the energy. • Electron carriers NAD+ and FAD become NADH and FADH2
Cellular Respiration • Stage 3: Electron Transport Chain (ETC) • Takes place on inner membrane of mitochondria. • Electrons picked up from Glycolysis and Krebs cycle are delivered here. • The ETC uses the electrons to change ADP into ATP. • Major source of energy!
Anaerobic Respiration • Fermentation: When O2 is not present, NAD+ is used in a different way and continues to make ATP through Glycolysis.
Anaerobic Respiration • Lactic Acid Fermentation • Pyruvate in the muscles are converted to Lactate when muscle cells operate without enough O2. • Fermentation enables glycolysis to produce ATP as long as glucose lasts. • Lactic Acid build up can cause sore muscles.
Anaerobic Respiration • Alcoholic Fermentation • In other organisms (ex. Yeast, fungus) pyruvate is broken down to ethanol (ethyl alcohol). • Glycolysis continues to make ATP. • Used in the preparation of many foods and beverages. • CO2 released by yeast causes bread dough to rise.