Lecture 6 Outline (Ch. 9, 10) I. Citric Acid Cycle II. III. IV. Electron transport chain & oxidative phosphorylation Anaerobic respiration Respiration with other molecules V. Chloroplasts VI. Light VI. Summary Steps of Respiration Glucose is OXIDIZED/REDUCED to. Oxygen is OXIDIZED/REDUCED to. Stages of respiration: Steps of Respiration 3. Citric acid cycle Mitochondrial matrix e- transfer: redox 1
3. Citric acid cycle few ATP so far now in mito. matrix 2 Acetyl CoA (2C) join oxaloacetate (4C) 2 citrate (6C) converted several steps, 4C lost (CO 2 ) 2 ATP made e- to carriers (NAD+, FAD) Where do the outputs go? In thinking about cellular respiration: a. What is/are the overall function(s) of glycolysis? b. What is/are the overall function(s) of pyruvate oxidation and the Krebs cycle? Stages of respiration: Steps of Respiration 4. ETC 2
Electron transport chain (ETC) ETC e- collection molecules embedded on inner mitochondrial membrane accept e- in turn e- ultimately accepted by O 2 (O 2 reduced to H 2 O) Electron transport chain (ETC) -inputs: per glucose, 10 NADH 2 FADH 2 -outputs: ATP (none yet) ~100 H+ (stored) 10 H 2 O Where do outputs go? 4. Chemiosmosis ATP synthase: inner mitochondrial membrane H+ stock-piled in inner membrane space = gradient chemiosmosis ion gradient to do work 3
3. Chemiosmosis ATP synthase: enzyme that makes ATP using H+ gradient H+ must enter matrix here Generates 1 ATP per ~3.4 H+ In thinking about cellular respiration: a. At what stage(s) in the overall process is each of the reactants used? b. At what stage(s) in the overall process is each of the products produced? C 6 H 12 O 6 + O 2 CO 2 + H 2 O + Energy Summary of respiration KNOW THIS DIAGRAM EXCELLENT SUMMARY 4
- anaerobic no O 2 no oxidative phosphorylation fermentation = extension of glycolysis - anaerobic Types of fermentation - 1. alcohol brewing & baking pyruvate converted to acetaldehyde acetaldehyde accepts e- to regenerate NAD+ ethanol produced - anaerobic Types of fermentation - 2. Lactic acid muscle fatigue & dairy industry pyruvate accepts e- to regenerate NAD+ lactate produced 5
Comparison of aerobic vs. anaerobic respiration: Aerobic Anaerobic initial e- acceptor: ATP per glucose: final e- acceptor: Let s say it takes 1,000 g of glucose to grow 10 g of yeast anaerobically. How many grams of glucose would it take (estimate approximately) to grow 10 g of yeast aerobically? Hint: If it takes X amount of glucose to grow 10 g of yeast without oxygen, what factor would you have to multiply or divide X by to grow 10 g of the same yeast with oxygen? other biomolecules Glucose catabolism one option Proteins: Catabolized into a.a. Amino group removed (pee out in urine) Fats: enter CAC or before If have more glucose than needed, can run backward to store energy as glycogen or fats! 6
Self-Check Step of Respiration Inputs Outputs CO 2 /H 2 O ATP produced e- carriers loaded Glycolysis 1 glucose 2 pyruvate None 2 net 2 NADH Coenzyme Junction Citric Acid Cycle Electron Transport Chain Oxidative phosphorylation & Chemiosmosis Fermentation Photosynthesis - overview Overall purpose: photosynthesis: light chemical energy complements respiration - light reaction: solar energy harvest - Calvin cycle: energy to organics Photosynthesis - overview 7
chloroplast recap Outer membrane Inner membrane Thylakoid membrane Intermembrane space Stroma Thylakoid space Photosynthesis - overview Chloroplast model: Photosynthesis - 1. light reaction: store energy & split water NADPH & ATP given off H 2 O + CO 2 + energy C 6 H 12 O 6 + O 2 In photosynthesis, water is OXIDIZED/REDUCED to and carbon dioxide is OXIDIZED/REDUCED to. 8
Redox Reactions Equation for photosynthesis CO 2 + H 2 O + light energy C 6 H 12 O 6 + O 2 photo synthesis Photosynthesis light absorption visible light ~380 to 750 nm chloroplast pigments absorb blue-violet & red/orange - transmit and reflect green Photosynthesis light absorption pigments: chlorophyll a -energy-absorbing ring -hydrocarbon tail accessory pigments - chlorophyll b - carotenoids - photoprotective 9
Photosynthesis light absorption chlorophyll a abs blue-violet, red ~400-450, 650-700 chlorophyll b & carotenoids abs broadly blue-violet 450-500 & 600-650 more wavelengths used for photosynthesis = more light energy absorbed If a car is red, which light wavelengths are reflected (NOT absorbed)? Self-Check 10