Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Cellular Respiration Cellular respiration is the process by which cells make energy. They use glucose and oxygen to produce carbon dioxide, water and ATP (usable energy) A common misconception Many people think “respiration” refers specifically to “breathing” Actually respiration refers to the processes of getting energy from food. All large animals (including humans) need to use oxygen to fully release the energy from food. That’s why the word respiration has also come to refer to breathing. The Summary Formula: C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy Glucose + oxygen carbon dioxide + water Enough energy is released during cellular respiration to produce up to 38 molecules of ATP 38 ADP + 38 PO4 38 ATP Energy Energy (ATP) Glucose Water mitochondrion Oxygen cell Carbon dioxide Where it all happens: Mitochondiron Stages of Respiration: Stage 1. Glycolysis (The splitting of sugars) Pyruvic Acid (CH3COCOOH) No oxygen available Lots of oxygen available Stage 2. Anaerobic Stage 2a. Aerobic (The fermentation of Pyruvic Acid) (the Krebs Cycle) Stage 2b. Aerobic A little energy (2 ATP / glucose molecule) (Electron Transport) A lot of energy (38 ATP / glucose) Glycolysis: Splitting the sugar Glucose is split into two 3-carbon molecules called pyruvic acid The Steps in Glycolysis are: Phosphate from ATP is joined to glucose, making a 6-carbon phosphate The 6-C phosphate breaks into 2 PGAL Hydrogen is removed and phosphate added to make two 3-carbon phosphates The two 3-C phosphates are converted to pyruvic acid, giving off enough energy for 4 ATP Glycolysis Diagram Glucose C6H12O6 CCCCCC 2 ATP 6 carbon-phosphate 2 PGAL 3 carbon-phosphate 2 ADP+P Energy “used” P-CCCCCC-P 2 NAD and 2P P-CCC P-CCC P-CCC-P P-CCC-P 2 NADH + H 4 ADP+P 2 Pyruvic Acid (pyruvate) CH3COCOOH 4 ATP CCC CCC Energy “gained” Uses of Pyruvic Acid The Pyruvic acid can be used for one of several different pathways, depending on the organism and the circumstances: 1. For alcoholic fermentation (in yeasts) 2. For lactic acid fermentation (in milk bacteria, and emergency systems in animals) 3. For aerobic respiration (the Krebs’ cycle) in most eukaryotes (plants and animals) In most animals, the pyruvic acid is first changed to Acetyl Co-A before being used in Krebs’ cycle Uses of Pyruvic Acid Glycolysis Pyruvic Acid Co enzyme A Alcoholic Fermentation Lactic Acid Fermentation Enzyme Reaction NAD NADH+H Acetyl Co-A CO2 Ethyl Alcohol CO2 Lactic Acid Anaerobic Respiration Krebs Cycle 2 CO2 Electron Transport 6 H2O Aerobic Respiration Lactic Acid Fermentation in Humans Humans normally undergo aerobic respiration (we use oxygen) Runners sometimes can’t fast enough to Under extreme exertion (or when breath supply their bodies with suffocating) we don’t get enough oxygen oxygen. Then we use lactic acid fermentation to produce some energy without oxygen. Build-up of lactic acid in muscles can cause pain and cramps. Lactic acid build-up causes pain, fatigue, and cramps Steps in aerobic respiration 1. 2. 3. 4. 5. 6. Pyruvic acid is converted to acetyl Co-A 2 carbons from Acetyl Co-A join onto a 4C compound (oxaloacetic acid) to make citric acid, a 6C compound (citric acid) Citric acid gives off one carbon dioxide to make a 5C compound (α-ketoglutaric acid) This gives off another carbon dioxide to make a 4C compound (succinic acid) The 4C compound rearranged (back into oxaloacetic acid), through two intermediate steps (fumaric acid and malic acid). Krebs cycle Captured hydrogen used to make energy The Enzyme Reaction Pyruvic acid + Co-enzyme A CO2 + Acetyl Co-A Acetyl Co-A carries two carbon atoms to the Krebs cycle, before being turned back into co-enzyme A Simplified Krebs Cycle Diagram C2 Acetyl Co-A Citric Acid C6 CO2 NADH+H Oxaloacetic Acid C44 NAD 5-carbon compound C5 (α-ketoglutaric acid) H2O H2O 4 Carbon compounds FAD NADH+H 4 Carbon compound C4 (fumaric acid & malic acid) (Succinic acid) FADH2 CO2 Advanced Krebs cycle (Optional Enrichment) CO2 Given off C o 2 Hydrogen Stored (NADH, FADH2) The Electron Transport Chain AKA: cytochrome system During the reactions of aerobic respiration, lots of Hydrogen has been captured in hydrogen storing compounds, including: 2 NADH from Glycolysis 2 NADH from conversion of Pyruvic Acid 6 NADH from the Krebs cycle 2 FADH2 from the Krebs cycle Many of the hydrogens have lost electrons Now the energy of those electrons & hydrogen ions are used to make ATP The Electron Transport Chain The Electron Transport Chain Along the inner membrane of the mitochondrion, electrons are passed from molecule to molecule The energy from these electrons is used to “pump” hydrogen ions (H+) into the space between the membranes The hydrogen ions diffuse back in, producing ATP by chemiosmosis (similar to photosynthesis) The hydrogen ions and electrons are combined with oxygen to form water. The Electron Transport Chain The simplified outcome of electron transport: The hydrogen atoms join with oxygen to make water. ADP Lots of ATP is produced +P 4 H+ + O2 +4e- H2O +ENERGY Energy ATP Remember, up to 38 ATP molecules can be produced from the complete respiration of a single glucose molecule. Other organic molecules, such as starches and lipids, can produce even more ATP if they undergo complete respiration. ATP is the energy exchange medium of the cell. It provides the energy for most cellular activity. Cellular Respiration Videos Cellular Respiration (Overview Lecture) Sugar Goes to ATP (Hey There Delilah) Cellular Respiration Song ( I Gotta Feeling) Cellular Respiration (Californication: too long for class) Student Made Respiration video (not too bad) Student-made Respiration song (dreadful and full of spelling mistakes, but mercifully short) Assignments on Respiration. Read Chapter 7, pp. 127 to 138. Read carefully the chapter summary on page 139. Do exercises on page 140 # 1 to 20 Draw a diagram to represent the Krebs’ cycle