Chapter 9 (Pages ) The Powerhouse Copyright Pearson Prentice Hall Overview of Cellular Respiration Cytoplasm Pyruvic acid Mitochondrion Electrons carried in NADH Electrons carried in NADH and FADH 2 Glucose Glycolysis The equation OMG! Its flipped! 2 NAD+ glucose C CC C CCCC CCCC P P P P 2 ADP 4 ADP 2 ATP 4 ATP 2 NADH PYRUVATE (pyruvic acid) Krebs Cycle (Citric Acid Cycle) Glycolysis Without O 2 Fermentation ETC (Where most ATP is made) With O 2 Two options all depends on presence O2! Anaerobic follows Glycolysis when oxygen is not present Not how the normal process of CR is supposed to go! Back-up plan! Fermentation releases energy from food molecules by producing ATP in absence of O2 The electrons stored in NADH are returned to Pyruvic Acid, letting the NAD+ go back to glycolysis and keep making ATP Alcoholic fermentation Lactic acid fermentation Used by yeasts, bacteria why bread rises Converts sugar into ethyl alcohol and CO 2 In many cells, the pyruvic acid that accumulates from glycolysis can be converted into lactic acid Produced in your body during rapid exercise Causes muscle soreness The equation for lactic acid fermentation after glycolysis is: Pyruvic acid + NADH lactic acid + NAD + In the presence of oxygen, cellular respiration proceeds from glycolysis to the Krebs Cycle Breaks down pyruvic acid into carbon dioxide Occurs in mitochondri al matrix Discovered in 1937 by Hans Krebs - biochemist The basic definition of Krebs Cycle: The breaking down of pyruvic acid into CO2 in a series of energy- extracting reactions Before the cycle starts turning Step 1 pyruvic acid enters the mitochondria Step 2 one carbon molecule from pyruvic acid breaks off to form CO2 Step 3 other two carbon atoms tack onto coenzyme A this molecule becomes acetyl coenzyme A Step 4 Acetyl CoA adds the two carbon acetyl group to a 4 carbon molecule THIS 6 CARBON MOLECULE IS CITRIC ACID! Step 1 citric acid loses a carbon That carbon becomes a CO2 molecule NAD+ picks up 2 electrons and H+ Step 2 the 5- carbon molecule loses a carbon That carbon becomes a CO2 molecule NAD+ picks up 2 electrons and a H+ ATP formed (only 1) Step 3 the 4- carbon molecule is ready to start the cycle again! FAD picks up 4 electrons and 2 H+ NAD picks up one last set of electrons and H+ One turn of the Krebs Cycle gives you these products: The ETC uses high-energy electrons from the Krebs cycle to convert ADP into ATP In eukaryotes, the ETC is a series of carrier proteins located in the inner membrane of the mitochondria In prokaryotes, the ETC is in the cell membrane 2 high energy electrons are transported through the ETC Their energy helps transport H+ through the membrane At the end of the ETC an enzyme (named Complex IV) is waiting patiently to snatch up the electrons and a couple H+ The enzyme combines the electrons, H+, and O2 H+ escape to intermembrane space THEY BUILDIN UP OVER THERE!!!!! H+ builds up in the intermembrane space, making it positively charged The H+ rush back to the negative membrane side As they pass, they cause ATP synthase to spin and make ATP In the presence of oxygen 36 total ATP molecules produced 38% of the total energy of glucose What happened to the remaining 62%? What can stop this process? Carbon monoxide disables Complex IV Electron carriers are not recycled Cellular respiration cannot continue ATP Synthase not as efficient Your body turns to fermentation When you need quick energy, how does your body produce it? Lactic Acid Fermentation Quick and easy When you need long term energy (longer than 90 seconds), where do you retrieve the ATP? Cellular Respiration Slowwwwwww, but higher amounts Not really, it happens a ton of times every second. Muscle stores (carbohydrates), fats