BIOL 1441 1st Edition Lecture 17 Outline of Last Lecture I. Substrate level phosphorylationII. GlycolysisIII. Citric acid cycleIV. Electron transport chainV. Cellular RespirationVI. ChemiosmosisVII. ATP synthase multisubunit complexOutline of Current Lecture I. Hydrogen gradientII. ATP productionIII. FermentationIV. Fermentation vs. cellular respirationV. Facultative anaerobesVI. Versatility of catabolismVII. PhotosynthesisVIII. Plant anatomyIX. Redox reactionX. Respiration vs. photosynthesisThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.XI. Sunlight Current LectureI. H+ Gradienta. Energy sourcesi. Electronsii. The gradient itselfb. ETC uses exergonic flow of electrons to pump H+ across the membranei. Low H+ in matrix (basic environment) high pHii. High H+ in inner membrane space (acidic environment) low pHc. How are H+ being moved?i. They are actively being pumped to intermembrane spaceii. Then they diffuse into the matrix1. ATP MADE IN THE MATRIXiii. Energy release- e- moves from less electronegative to more electronegative moleculeiv. Proton motive force- force drives H+ back across the membrane through ATP synthase channels1. DIFFUSIONII. ATP Productiona. 32 – 34 ATP, not exact numberi. DURING OXIDATIVE PHOSPHORYLATIONb. FADH2- transports enough H+ for 1.5 – 2 ATPi. FADH2 COMES IN AT A LOWER ENERGY LEVELc. TOTAL ATP PRODUCTION= 36-38 ATP 2 MORE FROM SUBSTRATE PHOSPHORYLATIONIII. Fermentation: no oxygena. Glycolysis can produce ATP without O2 (SAME IN AEROBIC RESPIRATION)i. Anaerobic respirationb. Fermentation generates ATP by substrate level phosphorylation (glycolysis)i. Problem: needs sufficient supply of NAD+ to accept electrons during glycolysis1. Mechanism is needed to recycle NAD+ to NADH (no ETC)ii. Solution: transfer electrons to pyruvate1. GIVES ELECTRONS TO PYRUVATE TO REGENERATE NAD+c. Fermentation- reactions that regenerate NAD +, which can be reused by glycolysisi. ATP produced from glycolysis onlyd. Fermentation- pyruvate reductione. PURPOSE OF FERMENTATION: OXIDIZE NADH INTO NAD+ TO KEEP GLYCOLYSIS GOING FORWARDf. FERMENTATION IS INEFFICIENT BECAUSE MOST OF THE ENERGY IS IN PYRUVATEAND THEY DON’T USE PYRUVATEg. Different Typesi. Alcohol fermentation1. Releases a CO22. Convers pyruvate into acetaldehydea. NADH GIVES ELECTRONS TO ACETALDEHYDE3. Acetaldehyde is REDUCED into ETOH(ethanol)4. OXIDIZING AGENT: ACETALDEHYDE5. REDUCING AGENT: NADHii. Lactic acid fermentation1. Pyruvate is reduced by NADH, forming lactate as an end product, with no release of CO22. Lactic acid fermentation by some fungi and bacteria is used to make cheese and yogurt3. Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarcea. When at peak exertion, enzymes cant keep up with cycleformation of lactic acid4. STEPS:a. NADH gives electrons directly to pyruvate. Pyruvate is reduced to lactic acidIV. Fermentation vs Cellular Respirationa. Both use glycolysis to oxidize glucose to pyruvateb. Both use NAD+ as an oxidizing agent (it oxidizes glucose)c. Difference: mechanism for oxidizing NADH back to NAD+ i. Different final electron acceptors: pyruvate or acetaldehyde in fermentation and O2 in cellular Rsd. Cellular Rs much more efficient, produces more ATP- releases stored energy in pyruvatei. Cellular Rs: 36-38 ATPii. Fermentation: 2 ATPV. Facultative Anaerobesa. Use either fermentation or cellular Rsi. CAN DO BOTH/SURVIVE ON BOTHb. Yeast & many bacteria are facultative anaerobesc. PROKARYOTES USE PLASMA MEMBRANE VI. Versatility of Catabolisma. Catabolic pathways funnel electrons from many kinds of organic molecules into cellular Rsb. Don’t usually obtain calories in form of glucosei. Fats, proteins, sucrose, starchii. Proteins are NOT a good source of energy (not a lot of hydrogen)1. Broken down into amino acids2. Amino groups must be removed-deamination(ammonia, urea-excreted in urine)3. Amino acids can be turned into pyruvate (glycolysis), acetyl CoA and citric acid cycleiii. Fats= good source of energy1. Glycerol is converted to glyceraldehyde-3-phosphate (glycolysis)2. Fatty acids are broke down by beta oxidation enter into citric acid cycle as acetyl CoAVII. Photosynthesis (Ps)VIII. Converts solar energy into chemical energy(food-sugar) a. Anabolic rxn- building organic moleculesi. Needs: Sunlight, CO2, H2Ob. Directly or indirectly, Ps nourishes almost the entire living worldc. Autotroph- “self feeders”i. Produce their own organic molecules from inorganic materialsd. Heterotroph- “other feeder”i. Unable to make their own food- consumers (humans)e. Photoautotrophsi. Most plants photoautotrophs- use energy of sunlight to make organic molecules from water & CO2ii. Only materials they require- water, CO2, minerals from soiliii. Ps occurs in algae, protists, prokaryotes f. Two Stages of Photo-synthesisi. Light rxns- (photo part) converts solar energy to chemical energy1. Occur in thylakoids2. Split water, release O2, produce ATP, & form NADPH 3. Light energy initially converted into chemical energy in form of NADPH & ATPii. Calvin cycle- (synthesis part) synthesizes sugar1. Occurs in stroma 2. Forms sugar from CO2, using ATP & NADPH from light rxn3. Sugar is produced in Calvin cyclea. Can only do so with NADPH and ATP produced in light rxn4. Dark rxn’s – do not require light directlyIX. Plant Anatomya. Chloroplasts- where photosynthesis happensb. Located in all green parts of plant- leaves, stem, unripened fruitc. Leaves- major locations of Psi. ½ million chloroplasts per sq millimeter of leaf surfaced. Green color is from chlorophyll- green pigment within chloroplastse. Chloroplastsi. Light energy absorbed by chlorophyll drives synthesis of organic molecules in chloroplastii. Chloroplasts found mainly in cells of the mesophyll- tissue in the interior of the leaf iii. Stroma- a dense fluid (do not confuse with stomata!)iv. Thylakoids- interconnected membrane sacs 1. CHLOROPHYLL LOCATED IN THE THYLAKOID MEMBRANESf. Stomatai. CO2 enters & O2 exits leaf through microscopic pores- stomataii. Water absorbed by roots delivered to leaves in veins1. Roots “breath” Absorb O2iii. Veins export sugar to rootsX. Photosynthesis Redox Reactionsa. Chloroplasts split water into hydrogen & oxygenb. Incorporate electrons of hydrogen into sugar molecules (put hydrogen electrons on CO2i. Hydrogen is oxidized (loses electrons)ii. CO2