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Cell Respiration Song Hee Bae IB1 Biology What is Cell Respiration? • The way to convert energy into a form that can be used within the cell. • : Controlled release of energy from organic compounds to form ATP. • Require energy for – Synthesizing – Active transport – Movement inside the cell • Energy is supplied by ATP • When ATP is split into ADP, energy released Glycolysis • • • • • • • All cells using glucose begin in the same way. Glucose enters the cell Takes place in cytoplasm Enzyme reactions 6 carbon glucose → two 3 carbon molecules 2 “Pyruvate” molecules Some energy released from breaking of the covalent bonds • Net gain of 2 ATP Anaerobic Cell Respiration • Cell deriving ATP completely without the use of oxygen • Glycolysis possible only if pyruvate is converted • “Fermentation” – Alcoholic fermentation – Lactic Acid fermentation Alcoholic Fermentation • • • • • • • • Yeast Generate net gain of two ATP Converts pyruvate to ethanol Ethanol is 2-carbon molecule One carbon atom in each is lost Given off as carbon dioxide Both are waste products Why put yeast in baking? Helps the dough to rise Lactic Acid Fermentation • • • • • • • • Occurs when insufficient supply of oxygen Ex) running person Excess pyruvate molecules are converted Pyruvate molecules are converted to lactic acid molecules No production of carbon dioxide Glycolysis possible only if pyruvate is converted Allows glycolysis to continue Used in food – Yogurt, kimchi, kefir, etc Aerobic Cell Respiration • • • • • • Occurs in cells with mitochondria Two pyruvate molecules enter mitochondria Each pyruvate loses a carbon → Acetyl CoA Each Acetyl CoA enters Krebs cycle Much efficient than anaerobic respiration – Breaks down (completely oxidizes) glucose – Products are carbon dioxide and water – Leaves no by-products – ATP per glucose is much higher The Krebs Cycle • Two more carbon dioxide molecules from each original pyruvate. • Some ATP is directly generated • Some is indirectly through later series of reactions Vocabulary • • • • • • Glucose: is a type of sugar the body uses for energy Glycolysis: is the metabolic pathway that converts glucose into pyruvate. Cell respiration: the process by which the chemical energy of "food" molecules is released and partially captured in the form of ATP. Aerobic cell respiration: The process by which the energy from glucose is released in the presence of oxygen Anaerobic cell respiration: The process by which the energy from glucose is released in the absence of oxygen Fermentation: process of deriving energy from the oxidation of organic compounds. Reference • Pearson Biology HL page 70-73 • Course Companion page 83-93 • Study Guide page 34 Thank You