Respiration I. Introduction A. What happens to the glucose made by photosynthesis 1. Converted to starch for storage 2. Is broken down to yield energy a. cellular respiration II. Cellular respiration: overview A. All Rxn in which energy is released to support cell life B. A controlled process 1. Comparisons a. Burning wood 1. A Rxn that releases stored energy 2. Uncontrolled a. energy released in a single chemical Rxn b. Wood  Heat + Light

b. Burning food 1. A Rxn that release stored energy 2. Controlled a. Energy is released during several steps b. The product of one Rxn. becomes the reactant in the next step of the Rxn. 3. Cells release energy in a series of steps

C. Cells transfer energy from food  ATP 1. Food (Starch)  Glucose 2. Cells transfer energy from glucose  ATP 3. ATP Broken down to yield energy a. ATP  CO2 + H2O + Energy D. Energy release overview 1. Step 1: Food (starch)  Glucose 2. Step 2: Glucose  ATP 3. Step 3: ATP  CO2 + H2O + Energy

III. Cellular respiration: A detailed look A. Glycolysis 1. Anaerobic stage of cellular respiration a. Does not require O 2 2. Occurs outside the mitochondria a. Cytosol 3. Glucose  2 pyruvic acid molecules a. A 3-carbon molecule 4. Energy a. 2 ATP molecules are needed to split glucose b. 4 ATP molecules formed by energy released from splitting glucose c. A net gain of 2 ATP d. 2 NADH molecules released 5. Glycolysis is only 3.5 % efficient a. For every glucose molecule broken down by glycolysis only 3.5% is converted to energy

B. Aerobic respiration 1. Occurs within the mitochondria 2. The Pyruvic acid molecules from glycolysis enter the mitochondria a. Each pyruvic acid  acetyl CoA 1. 1 NADH released/ pyruvic acid 3. The Krebs Cycle a. Acetyl CoA enters the Krebs cycle b. Through a series of 5 main steps 1. 3 NADH released/ Acetyl CoA 2. 1 FADH2 released/ Acetyl CoA 3. 1 ATP released/ Acetyl CoA Remember: For every glucose molecule entering glycolysis, 2 pyruvic acid molecules are created. This in turn creates 2 acetyl CoA molecules. This results in:2 NADH Pyruvic Acid 6 NADH 2 FADH2 Kreb Cycle 2 ATP For each glucose molecule

4. Electron Transport Chain a. The second stage of aerobic respiration b. Works similar to ETC in photosynthesis 1. For every NADH  3 ATP made 2. For every FADH2  2 ATP made c. Total ATP production  34 ATP

5. How efficient is aerobic respiration? a. 40% efficient 1. For every glucose molecule that enters aerobic respiration, 40% is converted to usable energy!! b. Comparison 1. An automobile is only 25% efficient