Chapter 9:Cellular Respiration& FermentationATP & EnergyStructure of ATPATP (Adenosine Triphosphate) shuttles energy for cellsATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups
ATP & EnergyThe bond between the terminal phosphate groups of ATPs can be broken, releasing organic phosphate and leaving ADP (adenosine diphosphate).Energy is released from ATP when the terminal phosphate bond is broken.This release of energy comes from the chemical change to a state of lower free energy (stabilizing), not from the phosphate bonds themselves.
Glycolysis & FermentationHarvesting Chemical EnergyCellular Respiration the break down of organic compounds (food, glucose, etc.) in cells to make energy, ATP molecules
C6H12O6 + 6O2 6CO2 + 6H2O + EnergyGlycolsysis Biochemical pathway that always starts cellular respiration!!!Does produce a small amount of ATP.Other products can follow two other pathways, depending on whether oxygen is present not.
GlycolysisATPOxygen AbsentOxygen PresentFermentation(anaerobic)Aerobic RespirationATPTwo (2) Types of Cellular RespirationAnaerobic Respiration respiration without oxygenAlso called fermentation
Aerobic Respiration respiration with oxygenII. GlycolysisBasics of Glycolysis glyco: sugarlysis: break upBegins to break down glucose & releases a small amount of energy (ATP)Occurs in the cytoplasm.All types of cellular respiration begin with glycolysis!!!!!!!!!!Major events in GlycolysisStart with (invest) 1 glucose, 2 NAD+, and 2 ATP molecules.Glucose, a 6-carbon molecule, is split into 2 PGAL, or glyceraldehyde-3-phosphate, molecules (each a 3-carbon molecule).Hydrogens are transferred from the 2 PGAL molecules to the 2 NAD+ molecules. This produces 2 NADH molecules.4 ATP molecules are then produced (2 ATP overall). This also produces 2 pyruvic acid molecules.Ends with 2 pyruvic acid, 2 ATP, 2 NADH molecules.Glycolysis
III. Anaerobic RespirationBasicsAlso known as FermentationDoes not make any ATP!Does remake NAD+, which goes back through Glycolysis to make 2 more ATP.2 Types of FermentationLactic Acid Fermentation2 H+ are removed from 2 NADH to make NAD+.Pyruvic acid is converted into lactic acid by gaining the 2 H+.NAD+ goes back through glycolysis to make more ATP.
(b) Lactic acid fermentation2 Lactate2 Pyruvate2 NADHGlucoseGlycolysis2 ADP 2 P i2 ATP2 NAD2 HFigure 9.17b13Figure 9.17 Fermentation.Alcoholic FermentationA CO2 molecule is removed from each pyruvic acid, creating acetaldehyde.2 H+ are removed from 2 NADH to make NAD+.Acetaldehyde is converted into ethyl alcohol by gaining the 2 H+.NAD+ goes back through glycolysis to make more ATP.
2 ADP 2 P i2 ATPGlucoseGlycolysis2 Pyruvate2 CO22 NAD2 NADH2 Ethanol2 Acetaldehyde(a) Alcohol fermentation2 HFigure 9.17a15Figure 9.17 Fermentation.
Mitochondria ReviewStructureSurrounded by a double membraneThe 2nd, inner membrane, is highly folded to increase surface area. Each fold is called a cristaeThe very interior of the mitochondria is called the mitochondrial matrix.
IV. Aerobic RespirationBasicsAerobic Respiration requires oxygen (O2)!Produces nearly 20 times more ATP than glycolysis alone.Begins with Glycolysis, followed by the Krebs Cycle, the Electron Transport Chain, and Chemiosmosis.Glycolysis Converts glucose into 2 pyruvic acids.Makes 2 NADH and a net of 2 ATP.Occurs in the cytoplasmPyruvic acid is converted into Acetyl CoA.The 2 Pyruvic Acids pass through both mitochondrial membranes into the mitochondrial matrix.As this happens, the 2 pyruvic acids reacts with a molecule called coenzyme A to form Acetyl CoA.2 NADHs and CO2 are produced.
Krebs CycleEach Acetyl CoA is broken down to make 1 ATP, 3 NADH, and 1 FADH2. 1st product is remade in the last step, so the Krebs Cycle can happen again.Remember, there are 2 Acetyl CoAs, so the Krebs cycle will happen twice.Our totals are therefore: 2 ATP, 6 NADH, and 2 FADH2.
NADH1Acetyl CoACitrateIsocitrate-KetoglutarateSuccinylCoASuccinateFumarateMalateCitricacidcycleNADNADHNADHFADH2ATP+ H+ H+ HNADNADH2OH2OADPGTPGDPP iFAD3245678CoA-SHCO2CoA-SHCoA-SHCO2Oxaloacetate22Figure 9.12 A closer look at the citric acid cycle.Electron Transport ChainOccurs across the inner membrane of the mitochondria (cristae).H+ ions are released from NADH and FADH2 into the mitochondrial matrix.The electrons in the hydrogen atoms are at a high energy level! The high energy electrons are passed along a series of molecules called the Electron Transport Chain.Electron Transport Chain (cont.)As the electrons move from molecule to molecule, they lose some of their energy.This energy pumps H+ out of the mitochondrial matrix, into the space between the two mitochondrial membranes.A high concentration of H+ builds up in this space.Electron Transport Chain
ChemiosmosisH+ ions diffuse from the high area of concentration made in between the 2 mitochondrial membranes to the low are in the matrix.Specifically the H+ ions move through a protein called ATP Synthase.As H+ ions move through ATP Synthase, ATP is made!34 ATP are made in chemiosmosis.The H+ ions then combine with oxygen to form water.Electron Transport Chain
Summary of Aerobic RespirationTotal ATP made aerobically: 38 ATPsGlycolysis = 2Krebs Cycle = 2Electron Transport Chain = 34