Cellular Respiration Summary Notes PDF

Cellular Respiration Harvesting Chemical Energy ATP AP Biology 2006-2007  Harvesting stored energy ▪ Energy is stored in organic molecules ◆ carbohydrates, fats, proteins ▪ Heterotrophs eat these organic molecules → food ◆ digest org...

Cellular Respiration Harvesting Chemical Energy ATP AP Biology 2006-2007  Harvesting stored energy ▪ Energy is stored in organic molecules ◆ carbohydrates, fats, proteins ▪ Heterotrophs eat these organic molecules → food ◆ digest organic molecules to get… ▪ raw materials for synthesis ▪ fuels for energy ⬥ controlled release of energy ⬥ “burning” fuels in a series of step-by-step enzyme-controlled reactions AP Biology  Harvesting stored energy ▪ Glucose ◆ catabolism of glucose to produce ATP glucose + oxygen → energy + water + respiratio carbon dioxide n + C6H12O6 + 6O2 → ATP + 6H2O + 6CO2 heat COMBUSTION = making a lot of heat energy RESPIRATION = making ATP (& some heat) by burning fuels in one step by burning fuels A in many small steps T enzyme P s AT O glu O P 2 co fuel 2 AP Biology carbohydrates) CO2 + H2O + heat se CO2 + H2O + ATP (+ heat)  How do we harvest energy from fuels? ▪ Digest large molecules into smaller ones ◆ break bonds & move electrons from one molecule to another ▪ as electrons move they “carry energy” with them ▪ that energy is stored in another bond, released as heat or harvested to make ATP loses gains reduce oxidized e- e- d + – + e + e - - reductio oxidation e n AP Biology - redox  How do we move electrons in biology? ▪ Moving electrons in living systems ◆ electrons cannot move alone in cells e ▪ electrons move as part of H atom p ▪ move H = move electrons loses gains reduce oxidized e- e- d + – + + H reductio oxidation n H oxidation C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP AP Biology He reductio  Overview of cellular respiration ▪ 4 metabolic stages ◆ Anaerobic respiration 1. Glycolysis ⬥ respiration without O2 ⬥ in cytosol ◆ Aerobic respiration ⬥ respiration using O2 ⬥ in mitochondria 2. Pyruvate oxidation 3. Krebs cycle 4. Electron transport chain C H O6 + AP Biology 6 12 6O2 → ATP + 6H2O + 6CO2 (+ heat)  glucose C-C-C-C-C- Overview C AT 2 P 10 reactions A 2 D ◆ convert fructose-1,6bP P glucose (6C) to P-C-C-C-C-C-C- 2 pyruvate (3C) P ◆ produces: DHAP G3P P-C-C- C-C-C- N 4 ATP & 2 NADH C P2H 2 A ◆ consumes: 2Pi D+ 2 2 ATP A ◆ net: 2Pi 4 D 2 ATP & 2 NADH P AT pyruvate 4 P AP Biology C-C-C  Cellular respiration AP Biology  Mitochondria — Structure ▪ Double membrane energy harvesting organelle ◆ smooth outer membrane ◆ highly folded inner membrane ▪ cristae ◆ intermembrane space ▪ fluid-filled space between membranes ◆ matrix ▪ inner fluid-filled space ◆ DNA, ribosomes ◆ enzymes outer intermembran membrane ▪ free in matrix & membrane-bound e inner space crista membrane e matri x What cells would have AP Biology a lot of mitochondria? mitochondria l  Oooooh! Form fits Mitochondria – Function function! Dividing mitochondria Membrane-bound proteins Who else divides like that? Enzymes & permeases bacteria! What does this tell us about Advantage of highly folded inner the evolution of eukaryotes? membrane? More surface area for membrane- Endosymbiosis! AP Biology bound enzymes & permeases  Oxidation of pyruvate ▪ Pyruvate enters mitochondrial matrix [ 2x pyruvate → → → acetyl CoA + CO2 C 3 NAD 2 C 1 C ] Where does the ◆ 3 step oxidation process CO2 go? ◆ releases 2 CO2 (count the carbons!) Exhale! ◆ reduces 2 NAD → 2 NADH (moves e-) ◆ produces 2 acetyl CoA ▪ Acetyl CoA enters Krebs cycle AP Biology  Count the electron carriers! acetyl CO2 pyruvate 3C 2C CoA NADH citrate NADH 4C 6C 4C reduction 6C This happens of electron twice for each CO2 carriers glucose NADH molecule 4C x2 5C FADH2 CO2 4C AT 4C AP Biology NADH P  Electron Carriers = Hydrogen Carriers H+ H+ H+ H+ ▪ Krebs cycle H+ H+ H H+ + produces large quantities of electron carriers ADP + Pi A ◆ NADH P T H+ ◆ FADH2 ◆ go to Electron Transport Chain! What’s so important about electron carriers? AP Biology  ATP accounting so far… ▪ Glycolysis → 2 ATP ▪ Kreb’s cycle → 2 ATP ▪ Life takes a lot of energy to run, need to extract more energy than 4 ATP! There’s got to be a better way! I need a lot more ATP! A working muscle recycles over AP Biology 10 million ATPs per second  There is a better way! ▪ Electron Transport Chain ◆ series of proteins built into inner mitochondrial membrane ▪ along cristae ▪ transport proteins & enzymes ◆ transport of electrons down ETC linked to pumping of H+ to create H+ gradient ◆ yields ~36 ATP from 1 glucose! ◆ only in presence of O2 (aerobic respiration) That sounds more O2 AP Biology like it!  Electron Transport Chain Building proton NADH → NAD+ + H gradient! e intermembrane space p H+ H+ H+ inner mitochondrial H → e- + H+ C membrane Q e– e – H e– FADH2 FAD H 1 NADH 2H+ + O2 H2 NAD + 2 NADH cytochrome cytochromeOc dehydrogenase bc complex oxidase complex mitochondrial matrix AP Biology What powers the proton (H+) pumps?…  Stripping H from Electron Carriers ▪ Electron carriers pass electrons & H+ to ETC ◆ H cleaved off NADH & FADH2 ◆ electrons stripped from H atoms → H+ (protons) ▪ electrons passed from one electron carrier to next in mitochondrial membrane (ETC) ▪ flowing electrons = energy to do work ◆ transport proteins in membrane pump H+ (protons) across inner membrane to intermembrane space H+ H+ H+ H H H H + + + + TA-DA!! H + H + H+ H+ H+ H H+ + Moving electrons do the work! C Q e– e– e – FADH2 FAD ADP 1 NADH 2H+ + O2 H2O + Pi NAD+ 2 A NADH cytochrome cytochrome c dehydrogenase bc complex oxidase complex T AP Biology P H+  Electrons flow downhill ▪ Electrons move in steps from carrier to carrier downhill to oxygen ◆ each carrier more electronegative ◆ controlled oxidation ◆ controlled release of energy make ATP instead of fire! AP Biology  “proton-motive” force We did it! H+ H+ H+ H+ ▪ Set up a H+ H+ H + H+ H+ gradient ▪ Allow the protons to flow through ATP synthase ▪ Synthesizes ATP ADP + Pi → ATP ADP + Pi Are we ATP there yet? H+ AP Biology  Chemiosmosis ▪ The diffusion of ions across a membrane ◆ build up of proton gradient just so H+ could flow through ATP synthase enzyme to build ATP Chemiosmosis links the Electron Transport Chain to ATP synthesis So that’s the point! AP Biology  Pyruvate from Intermembrane Inner H + cytoplasm space mitochondrial H + membrane Electron transpor C t Q system NADH e- 2. Electrons H+ provide energy 1. Electrons are harvested Acetyl- and carried to the e- transport system. to pump CoA protons across NADH e- the membrane. HO 2 Krebs e- 3. Oxygen joins 1 O FADH2 with protons to cycle 2 +2 O2 form water. 2H+ CO2 H+ ATP H+ ATP ATP 4. Protons diffuse back in down their concentration ATP Mitochondrial gradient, driving the synthase matrix synthesis of ATP. AP Biology  Taking it beyond… H+ H+ H+ ▪ What is the final Q e C – e– electron acceptor in e – FADH2 FAD 1 NADH O2 Electron Transport NAD 2H + + + 2 H2O O NADH cytochrome cytochrome c dehydrogenase bc complex oxidase complex Chain? 2 ▪ So what happens if O2 unavailable? ▪ ETC backs up ◆ nothing to pull electrons down chain ◆ NADH & FADH2 can’t unload H ▪ ATP production ceases ▪ cells run out of energy AP Biology ▪ and you die!  Fermentation ▪ Pyruvic acid moves to the next step ◆ If there is no oxygen = anaerobic ◆ If there is oxygen = aerobic AP Biology  Fermentation ▪ Fermentation – process by which cells release energy in the absence of oxygen ▪ Two types of fermentation: ◆ Alcoholic Fermentation ◆ Lactic Acid Fermentation AP Biology  Alcoholic Fermentation PYRUVIC _______ +_____ →__________ + ______ + _____ ALCOHOL CO 2 NAD + ACID ▪ Happens when yeast makes bread dough rise, CO2 bubbles make air spaces in bread. (Alcohol evaporates during cooking) ▪ Happens when: ◆ Yeast make beer and wine AP Biology  Lactic Acid Fermentation PYRUVIC _______ +_____ →______________ + ________ LACTIC ACID NAD + ACID ▪ Happens in muscles during exercise when body can’t get oxygen to tissues fast enough. ▪ Lactic acid builds up in muscles causing soreness. ▪ Bacteria use lactic acid fermentation to make: yogurt, cheese, sour cream, pickles, sauerkraut, kimchi AP Biology Fermentation (Alcoholic and Lactic Acid) AP Biology