Chpt 9 Cellular Respiration Food provides organisms with materials needed for growth, repair and energy. Carbohydrates are chemically stored energy needed by ALL living things calorie (scientific calorie) amount of energy that raises temperature of 1 gm of water 1 degree C (1.8F). * Calorie (capital C) used in food labels is really a kilocalorie (1000 scientific calories). 1g Glucose = 3,800 calories or 3.8 Calories Cellular Respiration process of releasing food energy by breaking down glucose with oxygen. * Cellular Respiration (releasing energy) is the OPPOSITE of Photosynthesis (storing energy) Cellular Respiration- 6O2 + C6H12O6 6CO2 + 6H2O + Energy Photosynthesis- 6CO2 + 6H2O + Energy 6O2 + C6H12O6 Step 1 Glycolysis (splitting sugar) - OCCURS IN Cytoplasm Glucose + 2 ATP 2 Pyruvic Acids + 4 ATP (net 2 ATP) + 2NADH END RESULT OF GLYCOLYSIS: 2 Atps 2 Nadhs 2 Pys Creates 4 ATP( net 2 ATP ) energy molecules 2 NADH electron carrier molecules ( 2 pairs of electrons & H+) 2 Pyruvic Acids
Step 2 Respiration (creating ATP energy from glucose) Aerobic Respiration ( with air ) releasing energy from Glucose with O2 Anaerobic Respiration (Fermentation) - releasing energy w/out O2 I. Anaerobic (Fermentation) - without O2 does not extract any additional energy from pyruvic acid. Occurs in Cytoplasm. 2 ATP from from Glycolysis are only energy molecules created. Pyruvic acid Temporary acceptor of electrons from NADH A. LACTIC ACID FERMENTATION in Animals/Bacteria Produces Lactic Acid (muscle fatigue/yogurt/cheese) In Muscles, Pyruvic acid temporarily accepts H2 & electrons from NADH changing to Lactic Acid Pyruvic Acid + NADH Lactic Acid + NAD+ O2 eventually enters muscles becoming final hydrogen acceptor and reverting Lactic to Pyruvate. Glycolysis Lactic Acid Fermetation Pyruvic Acid temporarily accepts E- & H+ from NADH Creating NAD+ to go back and continue Glycolysis
B. ALCOHOL FERMENTATION In Plants/Yeast Produces CO2 and Alcohol (Beer/Wine/Bread) Pyruvic Acid + NADH Alcohol + CO2 + NAD+ ALCOHOL FERMENTATION Summary of Energy created from ONE Glucose in Anaerobic Respiration (Fermentation) 2 ATP NET & 2 NADH } Both molecules created from Glycolysis. II. Aerobic Respiration extracting energy with O2 Inside Mitochondria to create 34 ATP molecules. After Glycolysis, 2 Pyruvic acids enter Mitochondria (uses 2 ATP for eukaryotes) 1. Kreb Cycle (Citric Acid Cycle) - A twice occurring series of energy extracting reactions where pyruvic acid is broken down to CO2 while producing ATP molecules. 2 Parts of Kreb Cycle Pt 1.Citric Acid Production 1 NADH X 2 Pyruvic = 2 NADH 1 CO2 = 2 CO2 Pt.2 Energy Creation 1ATP molecule is created. X 2 Pyruvic = 2 ATP 2 CO2 (waste gas) are created. 4 CO2 1 FADH2 electron carrier is created 2 FADH2 3 NADH electron carriers are created. 6 NADH Plus 2 ATP and 2NADH from Glycolysis
B) Electron Transport Chain uses high energy electrons (H2) to create ATP. Electrons (H2) from FADH2/NADH attract H+ ions across membrane. H+ ions build up on one side & rush through turning ATP Synthase creating ATP. Each NADH creates 3 ATP (10 NADH 8 from ETC and 2 from Glycolysis) 30 ATP Each FADH2 creates 2 ATP (2 FADH2 from ETC) 4 ATP 2 ATP from Glycolysis & 2 from Krebs Minus 2 ATP to move Pyruvate into Mitochondia 2 ATP Oxygen is the final acceptor of H2 electrons, forming H2O metabolic waste water. Result of Cellular Respiration = C6H12O6 + 6 O2 6 CO2 + 6 H2O + 36 ATP (Energy) Aerobic Respiration creates 18 times more efficient (36 ATP) than Fermentation (2 ATP from Glycolysis).
Aerobic Respiration Overview Oxidation-Reduction Reactions Oxidation When an atom or molecule loses electrons, it loses energy. Reduction - When an atom or molecule gains electrons, it gains energy. * When a substance loses electrons, another gains those electrons. Oxidation Reduction Reaction - Energy is passed from one substance to another by electrons. Hydrogen Acceptors Hydrogen - is a common atom involved in Oxidation-Reduction Reactions energy transfers. NAD+ and FAD are Coenzymes that act as Hydrogen acceptors. Muscle Fatigue and Oxygen Debt During long workouts, muscles use up O2 faster than can be breathed in and sent to muscles. That s why we keep breathing hard after we stopped a strenuous workout. NADH + FADH2 build up in muscle due to lack of O2 and can t drop off hydrogen electrons. Remember, O2 is the final acceptor of H2, forming the Metabolic waste water H2O. NADH + FADH2 unload their H2 on Pyruvic acid, changing it to Lactic Acid. Pyruvic acid becomes a temporary acceptor of H2, becoming Lactic acid. Lactic acid leads to soreness in muscles which goes away in a day as we breath in more O2. As more O2 enters muscles, it takes H2 from the lactic acid, converting it back to pyruvic acid. Oxygen Debt The amount of Oxygen needed to change Lactic acid back to Pyruvic Acid. (ex) Athletes sleeping in a pure O2 tent.