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http://www.clickatutor.com/mitochondria.jpg Cellular Respiration Campbell Chapter 9 Slide shows modified from: Glenbrook High School AP site http://gbs.glenbrook.k12.il.us/Academics/gbssci/bio/apbio/Index/index.htm & Dr. Chuck Downing http://gohs.tvusd.k12.ca.us/TeacherWebs/Science/CDowning/default.aspx http://www.inclusive.co.uk/downloads/images/pics2/tree.gif AUTOTROPHS ___________ use energy from sunlight or chemicals to make their own food In the last chapter green plants PHOTOSYNTHESIS used ________________ sunlight trap energy from __________ food (glucose) and make ______________ http://206.173.89.42/REALTYWITHALOHA_COM/piphoto/funny%20sun%20with%20sunglasses.gif Image from: http://ag.ansc.purdue.edu/sheep/ansc442/Semprojs/2003/spiderlamb/eatsheep.gif In this chapter we will learn how HETEROTROPHS ______________ get their energy by consuming other organisms. GLUCOSE We get our energy from the __________ plants made during _______________ PHOTOSYNTHESIS when we eat plants or eat animals that ate the plants. http://www.cibike.org/Eating.htm In this chapter, we will learn how this broken down glucose is ____________ by energy organisms and the _______ is stored as _______ ATP What kind of organisms do this? ALL LIVING THINGS NEED ENERGY! All organisms burn glucose for fuel plants fungi Animals (Including humans) bacteria PHOTOSYNTHESIS 6___________ CO2 +6_________ H2O + ___________ C6H12O6 + __________ 6O2 →_______________ CELLULAR RESPIRATION C6H12O6 + _________ 6 CO2 + __________ 6 H2O + __________ 6O2 →________ _____________ The two equations are exact opposites! ______________________________________________________________ http://www1.istockphoto.com/file_thumbview_approve/777814/2/istockphoto_777814_oil_bonus_pack.jpg REMEMBER: OIL RIG OXIDATION Is Loss of electrons Remove H Releases energy Exergonic REDUCTION Is Gain of electrons Add H Stores energy Endergonic OXIDATION Loss of hydrogen atoms Energy Gain of hydrogen atoms REDUCTION CELLULAR RESPIRATION happens __________ slowly in ________________. many steps If all the energy was released in one step… most would be lost as ____________________! light and heat http://plato.acadiau.ca/COURSES/comm/g5/Fire_Animation.gif THE BIG PICTURE PLAYED OUT BEFORE YOUR EYES... http://www.sumanasinc.com/webcon tent/animations/content/cellularrespi ration.html 10 ELECTRON TRANSPORT CHAIN • Prevents energy release in 1 explosive step • Allows energy to be released slowly in steps and captured as ATP • Electron route: food → NADH → ETC → oxygen Link to Example of Coupled Reaction with Delta G Values Look at middle of page Titled “How Free Energy Works” section: delta G values are shown for ATP hydrolysis and NADH http://www.chemistry.wustl.edu/~edudev/LabTutorials/Cytochromes/cytoch romes.html 12 MITOCHONDRIA = cell power plant Surrounded by ___________ DOUBLE membrane Outer membrane & Inner membrane (called _______________ ) CRISTAE Space between inner membrane & outer membrane = ____________________ INTERMEMBRANE SPACE Space inside cristae folds = _________________ MATRIX 14 Text ATP Synthase inner membrane impermeable to H+ ions; therefore creates a force/charge gradient or voltage difference; electropotential. 15 HIGH ENERGY ELECTRON CARRIERS FAD → FADH2 NAD+ → NADH http://courses.bio.indiana.edu/L104Bonner/Sp12/imagesSp12/L16/MPs.html GREAT ANIMATION OF ELECTRON PUSH!! WATCH THIS!! The first step in cellular respiration = _______________ GLYCOLYSIS Also called _________________________________ Embden-Meyerhoff Pathway CYTOPLASM • happens in the ________________ outside the mitochondria • occurs _________________________ with or without oxygen See glycolysis movie http://www.northland.cc.mn.us/biology/biology1111/animations/glycolysis.html • Details of glycolysis Steps 1– 3A fuel molecule is energized, using ATP. Glucose Step PREPARATORY PHASE (energy investment) 1 Glucose-6-phosphate 2 Fructose-6-phosphate 3 Arraugh! Like, this is way hard! Step 4A six-carbon intermediate splits into two three-carbon intermediates. Step 5A redox reaction generates NADH. Fructose-1,6-diphosphate 4 Glyceraldehyde-3-phosphate (G3P) 6 Steps 6– 9ATP and pyruvic acid are produced. ENERGY PAYOFF PHASE 5 1,3-Diphosphoglyceric acid (2 molecules) 7 3-Phosphoglyceric acid (2 molecules) 8 2-Phosphoglyceric acid (2 molecules) 2-Phosphoenolpyruvate (2 molecules) 9 Pyruvic acid (2 molecules per glucose molecule) Glycolysis (GLYKOS = ________ sweet LYSIS= ___________ Split apart ) ENERGY Requires ____________to get it started. SUBSTRATE LEVEL PHOSPHORYLATION = using energy from breaking a chemical bond of a substrate (like glucose)MITOCHONDRION to add a P directly from a phosphorylated molecule to ADP without a proton gradient. (glycolysis is substrate-level phosphorylation and NOT very efficient) PYRUVIC ACID MOVES TO NEXT STEP = ANAEROBIC IF THERE IS NO OXYGEN (______________) IF THERE IS OXYGEN (_____________) = AEROBIC Cellular respiration •Glycolysis: cytosol; glucose → pyruvate •Kreb’s Cycle: •mitochondrial matrix; •pyruvate → CO2 •NADH made Electron Transport Chain: cristae; NADH & FADH2 donate electrons → oxygen Pyruvate is transported into mitochondrion and Acetyl CoA produced For each pyruvate converted into acetyl CoA 1 molecule of CO2 is released; NAD+ ---> NADH; Krebs Cycle AnimationCoenzyme A (from B vitamin) Kreb’s Cycle = Citric Acid Cycle Krebs Cycle Animation OAA CITRIC ACID Kreb’s Cycle • Oxaloacetate (OAA) combines with 2 C’s from Acetyl CoA to make Citric acid • CoA recycles • 2 C atoms from pyruvate → exit as CO2 For 2 3 1 each pyruvate that enters: CO2 released NAD+ reduced to 3 NADH; FAD+ reduced to 1 FADH2 (riboflavin, B vitamin); 1 ATP molecule Electron transport chain ATP Synthase: The machine that keeps on turnin’........ • http://vcell.ndsu.edu/animations/atpgradien t/index.htm (great animation) • Real in-vivo video of ATP synthase action in live cell: • http://www.youtube.com/watch?v=QeHCAFKaWM8 • ATP cycle animation (slapping a phosphate on) – http://www.youtube.com/watch?v=Lx9GklK0xQg – Advanced animations (awesome if you have time) scroll down to metabolic/respiration » http://www.youtube.com/watch?v=Lx9GklK0xQg 26 27 Why don't both electron carriers make the same amount of ATP? NADH More on Making ATP FADH2 • 3 places in the chain make ATP • Electrons from NADH start “higher” in the waterfall, so they generate more ATP than FADH2 electrons, which start “lower” in the waterfall and miss one ATP-generating step. • Electron transport chain ETC includes Cytochromes Ubiquinone (Q) • NADH & FADH2 pass electrons pass down ETC • Energy from moving electrons concentrates H+ ions in __________________ intermembrane space • ________________: harnesses the flow of H+ back into thesynthase matrix make ATP ATP (oxidative phosphorylation) • ________ is final electron acceptor → ________ Oxygen H2O Cellular Respiration Grand Total • Glycolysis: →2 ATP (substrate-level phosphorylation) • Kreb’s Cycle:→ 2 ATP (substrate-level phosphorylation) • Electron transport & oxidative phosphorylation: 2 NADH (glycolysis) → 6ATP 2 NADH (acetyl CoA) →6ATP 6 NADH (Kreb’s) → 18 ATP 2 FADH2 (Kreb’s) → 4 ATP 38 TOTAL ATP from 1 molecule of glucose (-2 ATP to transport 2 pyruvate into mitochondria) NET of 36 ATP WHAT IF THERE IS NO OXYGEN? = ANAEROBIC IF THERE IS NO OXYGEN (______________) IF THERE IS OXYGEN (_____________) = AEROBIC Related metabolic processes Fermentation: • alcohol~ pyruvate →ethanol • lactic acid~ pyruvate → lactate ALCOHOLIC FERMENTATION PYRUVIC _______ ACID +_____ ALCOHOL + ______ CO2 + NAD →__________ _____+ • Happens when yeast makes bread dough rise • CO2 bubbles make air spaces in bread • Alcohol evaporates during cooking http://www.deliciousdelicious.com/archives/herb%20bread%201.jpg ALCOHOLIC FERMENTATION PYRUVIC _______ ACID +_____ ALCOHOL+ ______ CO2 + NAD →__________ _____+ Used to make alcoholic beverages http://www.firstpath.com/images/alcohol.jpg LACTIC ACID FERMENTATION PYRUVIC _______ ACID +_____ + LACTIC ACID NAD →______________ + ________ Happens in muscles during exercise when body can’t get oxygen to tissues fast enough. Lactic acid builds up in muscles causing soreness http://www.miranda.com/library.en/Images/Pictures/girls-runners.jpg LACTIC ACID FERMENTATION PYRUVIC _______ ACID +_____ + LACTIC ACID NAD →______________ + ________ Happens when bacteria are used to make foods and beverages like yogurt, cheese, buttermilk, sauerkraut, kimchi http://chronicle.augusta.com/images/headlines/032200/DANNON_YOGURT.jpg http://www.reillydairy.com/natural_cheese.html WHY DO FERMENTATION? WHY NOT JUST KEEP MAKING ATP USING GLYCOLYSIS? WITHOUT OXYGEN, PYRUVIC ACID builds up ___________ and all the NAD+ carriers get full. _______ Eventually glycolysis will NAD+ PYRUVIC ACID +_____ _______ + CO NAD →ALCOHOL __________ + ______ 2 + _____ LACTIC ACID + NAD ______ You get the NAD+ carriers back FERMENTATION HAPPENS so cells REGENERATE the NAD+ can ____________________ needed to keep glycolysis going FACULTATIVE ANAEROBES __________________________ = organisms that can make ATP using either fermentation or cellular respiration Ex: yeast and many bacteria With oxygen pyruvate → Krebs cycle Without oxygen → fermentation Organisms can use a variety of molecules for fuel Beta oxidation= __________________= breakdown of fatty acids into 2 carbon fragments that enter Krebs cycle as acetyl CoA 1 g of fat → twice as much ATP as 1 g of carbohydrate Evolutionary Significance • Most widespread metabolic pathway… suggests ancient prokaryotes probably used glycolysis to make ATP before oxygen was present • Earliest fossil bacteria present 3.5 billion years ago but large amounts of oxygen not present until 2.7 billion years ago • Glycolysis happens in cytoplasm without membrane bound organelles suggests it was found in early prokaryotic cells since eukaryotes appeared 1 billion years after prokaryotes (Endosymbiotic theory) VOCAB OVERLOAD ? CHEMIOSMOSIS = Generation of ATP from a proton gradient. It occurs in all living things Chloroplasts do it to make ATP in light reactions Mitochondria do it to make ATP following ETC http://student.ccbcmd.edu/~gkaiser/biotutorials/energy/atpsynthase_il.html Prokaryotes create gradient across cell membrane to make ATP to pump nutrients & waste and move flagella PHOTOPHOSPHORYLATION = Using hydrogen gradient generated by thylakoid membrane during the light reactions of photosynthesis to make ATP CHLOROPLAST OXIDATIVE PHOSPHORYLATION = using proton gradient created by electron transport chain in cristae membrane to make ATP MITOCHONDRION SUBSTRATE LEVEL PHOSPHORYLATION = using energy from breaking a chemical bond to add MITOCHONDRION aP directly from a phosphorylated molecule to ADP without a proton gradient Feedback mechanisms control cellular respiration (All arrows are reversible) 49 http://www.wiley.com/college/boyer/0470003790/animations/glycolysis/glycolysis.htm 50 Many Regulatory Steps Control Cell Respiration • Main regulatory step in cell respiration occurs at beginning during glycolysis. • An enzyme called PFK (phosphfructokinase) plays major role in regulating ATP production in Kreb’s. • http://www.wiley.com/college/fob/quiz/quiz14/14-22.html • Allosteric regulation of phosphofructokinase sets the pace of respiration. • This enzyme catalyzes the earliest step that irreversibly commits the substrate to glycolysis. • Phosphofructokinase is an allosteric enzyme with receptor sites for specific inhibitors and activators. • It is inhibited by ATP and stimulated by AMP (derived from ADP). ◦ When ATP levels are high, inhibition of this enzyme slows glycolysis. ◦ As ATP levels drop and ADP and AMP levels rise, the enzyme becomes active again and glycolysis speeds up. 51 DNP: DiNitroPhenol; the “ATP uncoupler” (weight loss gone bad) • Uncoupling reagents (uncouplers) are lipid-soluble weak acids. For example, H+ (shown in red) can dissociate from the hydroxyl group of the uncoupler dinitrophenol. • Uncouplers dissolve in the membrane, and function as carriers for H+ • This makes inner membrane of mitochondria PERMEABLE to H ions • Uncouplers block oxidative phosphorylation by dissipating the H+ electrochemical gradient. (There is no longer an electric potential to PUSH the ATP synthase). • The motion of H+ diffusion is lost as heat and does NO WORK; INCREASED FATTY ACID AND AMINO ACID METABOLISM; LOW ATP LEVELS AS GLYCOLYSIS IS INCREASED; PFK NO LONGER INHIBITED BECAUSE ATP LEVELS ARE LOW... 52 Protein Structure Flashback!! PFK (Phosphofructokinase) • http://www.wiley.com/college/boyer/04700 03790/structure/pfk/pfk_intro.htm • Example of ALLOSTERIC control; addition and removal of phosphates is the #1 regulatory mechanism of biological pathways. • Enzymes that ADD a phosphate group are called KINASES (“Kinetic/motion/”turn on”) because they ACTIVATE another molecule. • http://www.rpi.edu/dept/bcbp/yesterday/molbiochem/MB 53 53 Web/mb1/part2/glycolysis.htm#animat2 CELL RESPIRATION RAP!! • http://www.youtube.com/watch?v=VCpNk9 2uswY 48 54