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Outline. I. Cellular Respiration Glycolysis The Kreb’s cycle or (Citric Acid Cycle) Electron Transport Chain Chemiosmosis. Cellular Respiration Overview. Cellular Respiration is the process that releases energy by breaking down food molecules in the presence of oxygen.
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Outline I. Cellular Respiration Glycolysis The Kreb’s cycle or (Citric Acid Cycle) Electron Transport Chain Chemiosmosis
Cellular Respiration Overview • Cellular Respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. • Transformation of chemical energy in food into chemical energy cells can use: ATP • These reactions proceed the same way in plants and animals. • 6O2 + C6H12O6 6CO2 + 6H2O + Energy • Oxygen + Glucose Carbon Dioxide + Water + Energy
Cellular Respiration Overview • Breakdown of glucose begins in the cytoplasm in the process of glycolysis • At this point the biochemical pathway can go in one of 2 directions: • Anaerobic cellular respiration (aka fermentation) • Aerobic cellular respiration
C.R. Reactions • Glycolysis • Series of reactions which break the 6-carbon glucose molecule down into two 3-carbon molecules called pyruvate • Process is an ancient one-all organisms from simple bacteria to humans perform it the same way • Yields 2 ATP molecules for every one glucose molecule broken down • Yields 2 NADH per glucose molecule (NAD is a “cousin” of NADP – works the same way) • Occurs with or without oxygen
Aerobic Cellular Respiration • Oxygen required=aerobic • Consists of two biochecmical pathways which occur in a specialized structure within the cell called the mitochondria • 1. Krebs Cycle • 2. Electron Transport Chain
Kreb’s Cycle • Operates under aerobic conditions only. • Oxidizes the two-carbon acetyl group in acetyl CoA to C02 • Produces reduced coenzymes NADH and FADH2 and ATP directly
Production of pyruvate, & citric acid cycle take place in matrix
Electron Transport Chain • Occurs in cristae of the mitochondria • A series of coupled oxidation/reductiona reactions where electrons are passed like hot potatoes from one membrane-bound protein/enzyme to another before being finally attached to a terminal electron acceptor (usually oxygen or NADPH). • 34 ATP are formed by this process. • The final electron acceptor is an oxygen atom. The electron-oxygen combination + 2 hydrogen = H20
Chemiosmosis • The actual production of ATP happens through the process of chemiosmosis • Similar to the proton gradient in photosynthesis – the energy of the protons converts ADP ATP
Energy Tally • 36 ATP for aerobic vs. 2 ATP for anaerobic • Glycolysis 2 ATP • Kreb’s 2 ATP • Electron Transport 34 ATP 38 ATP