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Published bySara Fitzgerald Modified over 8 years ago
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CONVERTS ENERGY IN FOOD TO ENERGY IN ATP
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Involves over 25 chemical reactions Occurs in cytoplasm and mitochondria Can be divided into three main stages: 1) Glycolysis 2) The Krebs cycle 3) The electron transport chain
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1 st Stage: Glycolysis - cytoplasm—anaerobic ( no O 2 needed ) 2 nd Stage: Krebs Cycle - mitochondria—aerobic ( O 2 needed ) 3 rd Stage: Electron Transport Chain - mitochondria—aerobic ( O 2 needed )
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Does NOT require oxygen anaerobic First step in cellular respiration Occurs in cytoplasm Occurs in ALL organisms One glucose molecule is split to form two molecules of pyruvic acid
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Energy investment phase: 2 ATP needed to start reaction Energy harvest phase: 4 ATP produced Net gain: 2 ATP
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Envelope has inner and outer membranes Inner membrane: Very highly folded provides increased surface area Has many sites where cellular respiration can occur Encloses thick fluid matrix
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Occurs in matrix of inner mitochondrial membrane Aerobic – O 2 needed 2 Pyruvic acid 2 Acetyl CoA + 2 CO 2 2 Acetyl CoA 4 CO 2 + 2 ATP Net result: 2 ATP produced
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Occurs on inner mitochondrial membrane Also called oxidative phosphorylation or chemiosmosis Aerobic—requires O 2 Electron transport chain works with H + ions and ATP synthase (proteins in membrane) to produce ATP Generates up to 34 ATP per original glucose molecule
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GLYCOLYSIS = 2 ATP KREBS CYCLE = 2 ATP ELECTRON TRANSPORT CHAIN / ATP SYNTHASE = 34 ATP 38 ATP This production results only if O 2 is present
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SOME CELLS CAN HARVEST ENERGY WITHOUT OXYGEN
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Process that makes ATP without O 2 ATP produced in fermentation comes entirely from glycolysis Produces no additional ATP When O 2 is not present there is an overall net gain of 2 ATP per glucose molecule Two major types of fermentation: Lactic acid fermentation Alcoholic fermentation
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Occurs in muscle cells when O 2 supply is too low Cellular respiration continues but fermentation is main ATP source Produces lactic acid - waste product Results in muscle soreness after strenuous exercise Relieved after O 2 supply restored
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CAUSES MUSCLE PAIN AND CRAMPING
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Yeast: alcoholic fermentation Produces ethyl alcohol instead of lactic acid under anaerobic conditions Used in brewing industry Released CO 2 makes champagne and beer bubbly Used by bakers to make bread rise
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Fungi & Bacteria: produce lactic acid like muscle cells Used to flavor yogurt, some cheeses Other fermentation processes: Soybeans soy sauce Cabbage sauerkraut
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