CHAPTER 9 - CELLULAR RESPIRATION
CELLULAR RESPIRATIONProcess that releases energy by breaking down food molecules in the presence of oxygen
6 O2 + C6H12O6 --> 6 CO2 + 6 H20+ATP oxygen + glucose --> carbon dioxide + water + energy
3 Stages of Cellular RespirationGlycolysisKrebs CycleElectron Transport Chain
Each stage captures some of the chemical energy available in food molecules and uses it to produce ATP
Energy Molecules of Cellular RespirationIn cellular respiration, several molecules are used as energy carriers. These molecules carry energy from one step of cellular ADP + P = ATPNAD + H = NADHFAD+ + H2 = FADH2
GLYCOLYSISGlycolysis First step in releasing the energy of glucose.A molecule of glucose is broken into two molecules of pyruvic acid (a 3-carbon compound).takes place in the cytoplasmdoes not require oxygen - anaerobic
GLYCOLYSISRequires: 1 Glucose molecule (C6H12O6), 2 ATPProduces: 2 ATP, 2 NADH and 2 pyruvic acid
Second Stage: Fermentation or Krebs CycleGlycolysis can be followed by fermentation or the Krebs cycle depending if oxygen is present. Fermentation will occur if no oxygen is present.Krebs Cycle will occur if oxygen is present.
Fermentation Krebs CycleAnaerobic (no oxygen)Aerobic (oxygen)
Without Oxygen - FermentationAnaerobic - without the presence of oxygenFermentation - releases energy from food molecules in the absence of oxygentwo types: Alcoholic and Lactic Acid FermentationOccurs in the cytoplasm
Types of FermentationAlcoholic - causes bread to rise, used to make beer and wineLactic Acid - produced in muscles during rapid exercise when body cant supply enough O2causes painful, burning sensation and muscle soreness
With Oxygen - Krebs CycleAerobic - in the presence of oxygenKrebs Cycle also called Citric Acid CycleKrebs Cycle - 2nd stage of cellular respiration, in which pyruvic acid is broken down into CO2 in a series of energy-extracting reactions, creating energy molecules.Occurs in the mitochondria
Krebs CycleRequires: 1 Pyruvic AcidProduces: CO2, NADH, FADH2, ATP
Krebs CycleAs a pyruvic acid molecule enters the mitochondria, a carbon is removed, forming CO2.Carbons continue to be rearranged, releasing more CO2, while allowing the energy carriers to be charged.This cycle will happen twice for every molecule of glucose broken down in glycolysis.
Third Stage: Electron Transport ChainThe electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP into ATP. Occurs in the mitochondrial matrix.
Electron Transport Chain (ETC)Requires: NADH, FADH2, ADPProduces: H2O, NAD, FAD, ATP
Electron Transport ChainThe Krebs Cycle generates high-energy electrons that are passed to NADH and FADH2.The high-energy electrons (H+) from NADH and FADH2 are used up and passed along the proteins in the ETC.
Electron Transport Chain
Oxygen serves as the final electron acceptor forming a water molecule.As H+ ions move through the ETC, ATP synthase spins adding ADP to P forming ATP.
Cellular Respiration Totals1 molecule of glucose produces:2 ATP in glycolysis34 ATP in Krebs Cycle and Electron Transport ChainwaterCO2
Types of EnergyQuick Energy - Muscles only contain enough ATP for a few seconds of intense activity. Then, muscle cells produce their ATP by lactic acid fermentation. Long Term Energy - Cellular Respiration is the only way to generate a continuing supply of ATP energy is released more slowly than fermentation, which is why athletes have to pace themselves15 to 20 min. of activity from carbohydrate stored in the bodyafter 20 min., energy comes from break down of fats
Photosynthesis vs. RespirationPhotosynthesis and cellular respiration take place in opposite directions!
Photosynthesis: Use light energy to build a sugar.carbon dioxide + water + light energy sugars + oxygen
Respiration: Break down sugar to release energy.oxygen + sugars carbon dioxide + water + energy
Photosynthesis vs. RespirationPhotosynthesis:Use light energy to build a sugar.Process that deposits or captures energy.Removes carbon dioxide from the atmosphere. Releases oxygen into the atmosphere.
Photosynthesis vs. RespirationRespiration:Break down sugar to release energy. Process that withdraws or releases energy.Removes oxygen from the atmosphere. Releases carbon dioxide into the atmosphere.