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Breathing and Cellular Respiration INTRO • Fast and slow twitch muscles What kind of runner are you? • LONG DISTANCE RUNNING • Slow-twitch fibers • for repeated long contractions • SPRINTING or WEIGHT LIFTING • Fast-twitch fibers • Contract more quickly and powerfully What makes these muscle fibers so different? • SLOW TWITCH • FAST TWITCH • breaks down • breaks down glucose to glucose to get ATP get ATP AEROBICALLY ANAEROBICALLY (using oxygen) (not using oxygen) SLOW MUSCLES • 1. Thin fibers • 2. have many mitochondria • Many myoglobin FAST MUSCLES • Thicker fibers • Fewer mitochondria • Less myoglobin • (“white meat) What happens if not enough oxygen is available? • Glucose is not completely broken down and lactic acid is formed (a larger molecule) that makes muscles ache Big Question for Chapter 6 • How do our cells obtain O2 for cellular respiration and dispose of CO2? 6.1 Breathing • Isn’t that how we obtain oxygen? • Breathing = taking in oxygen in our lungs and removing carbon dioxide as we exhale Respiration Really is... • Cellular respiration = breakdown of organic molecules (for energy) in the presence of oxygen (in mitochondrion) 6.2 Cellular Respiration • C6H12O6 + 6O2 6CO2 + 6H2O + ATP > Glucose Bank • Break glucose bonds • Stored in ATP ATP glucose Glucose contains Energy: • 1 gram glucose = 4 kcal of energy • What are kcal? Kilocalories • 1 kilocalorie = 1000 calories 6.3 Need heat to stay alive • 75% of energy of daily food just to maintain • 2,200 kcal of energy per day needed for average adult Calculate • Walking at 3 mph, how far • HINT: (p. 91) would you have Walking 3 mph to travel to consumes per “burn off” the hour 158 kcal equivalent of an • 475/158 = 3 hrs. extra slice of pizza, which has • 3 mph X 3 = 9mi about 475 kcal? 6.4 Just how DO our cells extract energy from organic fuel molecules? • The glucose is dismantled and the energy stored in the bonds is carried by electrons. We don’t see e-, but we see H atoms. • C6H12O6 + 6O2 6CO2 + 6H2O + ATP • (hydrogen atom = • one proton and one electron) > What drives this to happen? • OXYGEN • A strong tendency to pull electrons from other atoms 6.5 Redox Reaction • Movement of electrons from one molecule to another is an oxidationreduction reaction Redox reaction • Oxidation • Reduction • loss of • addition of electrons from electrons to one substance another substance • Loss of H • Gain of H • "Leo goes Ger” • Loss of electrons = oxidation • Gain of electrons = reduction Key Players of Redox Reactions • Dehydrogenase • NAD+ • Enzyme • nicotinamide adenine • Remove H atoms dinucleotide • coenzyme • used to shuttle electrons How NADH becomes a “Hydrogen Carrier” • NAD+ + 2H • picks up 2 e- and • e- 2H+ and 2e- dehydrogenase NADH2 Electron Carrier • A.k.a. “hydrogen carrier” • Empty With e-/H eNAD+ NADH NADH p. 93 • C4H6O5 • Oxidized • NAD+ • Reduced C4H2O5 NADH How do we get energy? • Big molecules in food break apart • Released electrons carried to NADH • Energy to ATP’s • You can now use ATP energy 6.6 • Which has more energy? NAD+ NADH Why? NADH has picked up an e- 6.6 ETC • Electron Transport Chain NADH brings e- • Pass e- from higher energy to lower energy state NAD+ So… •NAD+ can be recycled over and over ETC • ETC Animation (click) • Note each carrier molecule has a greater affinity for e- than its uphill neighbor Where is the ETC? • Inner membrane of the Mitochondrion Sing the ETC Song • To the tune of “Buffalo Gals Won’t you Come Out Tonight”? 6.7 Chemiosmosis • Movement of solutes across a membrane from where they are MORE concentrated to where they are LESS concentrated. • Movement of H+ ions (click here to see the proton H+ pumps) “Down the Gradient” Note more H+ ions on one side of the membrane Went “against the gradient” and see energy was used to do this Chemiosmosis • Diffusion of excess H+ ions across a membrane from high to low concentration • ADP + Pi = ATP ATP Synthase • ATP Synthase Animation (click here to see the ATP synthase move H+ ions “against the gradient”) • ATP Synthase Animation (click here) Makes ATP • Energy is generated from the movement of H+ ions …enough to cause a phosphate to join ADP to form ATP Chemiosmosis and ETC working together on inner membrane • ETC and Chemiosmosis Together NADH and FADH2 carry protons (H+) and electrons (e-) to the electron transport chain Mitochondrion: Site of Cellular Respiration • Mitochondrion Cellular Respiration (be sure to see the cool rotating ATP Synthase and the end of the program) • Peter Mitchell (1920 - 1992) • Developed the theory of chemiosmosis • Nobel Prize 1978 2 Ways to Make ATP • Substrate-level • Chemiosmosis phosphorylation • does not involve a membrane • makes only small amounts of ATP • diffusion through a membrane of particles produces more ATP 6.8 3 Stages of Cellular Respiration 1. Glycolysis 2. Krebs Cycle 3. ETC/Chemiosmosis Glycolysis -Breaks down glucose into pyruvic acid -Occurs in cytoplasm -means “splitting of sugar” Glycolysis • Start with 6-carbon glucose and breaks into two 3-carbon pyruvic acid molecules (or pyruvate) Glycolysis Animation • Glycolysis actually has 9 steps…but you only need to learn that these molecules formed between glucose and pyruvic acid are called • intermediates Glycolysis: What do I need to know? • Needs 2 ATP to get started • Makes 4 ATP • Splits glucose into two pyruvates • Makes NADH (an e- carrier) • NET GAIN 2 ATP’s But... •Pyruvic acid itself does not enter the Krebs cycle 6.10 “Grooming” Pyruvic Acid Haircut and Conditioning “HAIRCUT” “CONDITIONING” As NADH is reduced to NAD+…pyruvic acid is oxidized (carbon atom removed as Coenzyme A CO2) (from B vitamin) joins the 2-c fragmen MAKES-Acetyl Coenzyme A or CoA 6.11 Ready to GO • The Acetyl-CoA is now ready to enter the Krebs cycle Hans Krebs (1900-1981) Yeah, he got a Nobel Prize, too Krebs Cycle • Only 2-C of acetyl participates • (Coenzyme A is recycled) • Occurs in mitochondrial matrix Also Called TCA cycle tricarboxylic acid which is also citric acid (the other 4-C)…so also called citric acid cycle Krebs cycle (cont.) • strips off a carbon as CO2 • makes 4 ATP • makes 10 NADH • makes 2 FADH2 One cycle 6.12 Mitochondrion Note many folds (cristae) of inner membrane This increases surface area Electron Transport Chain in inner membrane of the Mitochondrion Electron Carriers • In Glycolysis • NAD+ • In Cellular Respiration • NAD+ • FAD Final Electron Acceptor • Oxygen • It is what drives the reaction and pulls the electrons away from their bonds. Final Products • Water (from oxygen and hydrogens) • CO2 when it was pulled out of Krebs cycle • ATP formed mostly from chemiosmosis/ETC 6.12 Chemiosmosis/ETC Powers Most of ATP Produced • Glycolysis -2 ATP • Krebs Cycle - 2 ATP • Chemiosmosis/ ETC - 34 ATP • NET TOTAL = 38 ATP Chemiosmosis and ETC • H+ ions can only pass through a special port ATP synthase (see knobs on cristae) ATP synthase • As H+ ions move through the ATP synthase port it powers the formation of ADP + Pi to ATP • • Animation of ATP synthesis in Mitochondria OVERALL ANIMATION • Cellular Respiration Animation and Explanation Burn 1 glucose molecule • ~ 100 ATP molecules • 100% energy released Glucose in the body • Only about 40% goes to use in ATP molecules • Rest lost as heat 6.15 YEAST FERMENTATION • In yeast, can they make enough energy without oxygen? • YES • Is this aerobic or anaerobic? • anaerobic Remember the Yeast Lab? • Put glucose with yeast and what were the two byproducts? • Carbon dioxide and ethyl alcohol What was the side step? • NAD+ was replenished • The taxi cab loses its e- and is now available to pick up more electrons. If all the taxi cabs are full, the reaction would stop. Alcoholic Fermentation • Is using yeast or bacteria to convert glucose to alcohol. Ethanol is Toxic to Yeast • So what do they do with it? • Yeast release the waste to the surroundings. What happens if … • The yeast makes too much ethanol? • They die XX XX Lactic Acid Fermentation • In your muscles • As you exercise, lactic acid is formed. • You also breath out carbon dioxide. Where does the lactic acid go? • Carried to liver • Here lactic acid is converted back to pyruvic acid. Where is lactic acid used? • Commercially: • Lactic acid fermentation is used by bacteria in the dairy industry to produce: Cheese and yogurt Strict Anaerobes • Require anaerobic conditions and are poisoned by oxygen • Methanogens are strict anaerobes that release methane as a waste product of cellular metabolism. Many live in mud at the bottom of lakes and swamps because it lacks oxygen, and some (enteric bacteria) live in the intestinal tracts of animals Facultative Anaerobes • Can make ATP either by fermentation or by chemiosmosis, depending on whether oxygen is available or not Facultative Example • Vibrio parahaemolyticus halophilic, facultative anerobic, rod bacterium that causes a foodborne illness known as seafood poisoning. Making Beer • Large fermentation tanks to make beer and wine have a one-way valve so no oxygen gets in…only the carbon dioxide out. 6.13 ROTENONE POISON • Binds with first of the proteins of the ETC • used to kill insects and fish pests • Cyanide and carbon monoxide bind with third protein of ETC • Antibiotic oligomycain blocks H+ ions through ATP synthase channel • Used to combat fungal infections on the skin Uncouplers • Make the membrane of the mitochondrion leaky to H+ ions • So…can’t make ATP • DNP prescribed as weight-loss pills, but banned 6.14 Review of ATP YIELD (Ideally) • • • • Need 4 ATP to start glycolysis Glycolysis makes 2 ATP Krebs Cycle makes 2 ATP ETC/Chemiosmosis makes 34 ATP • TOTAL about 38/ molecule of glucose Where does it all come from? • 1 NADH = 3 ATP • 1 FADH2 = 2 ATP