Section 8.3Cellular Respiration
Edward Terzian, Jr.
*Concept MapCellular Respiration3 StagesGlycolysisAnaerobicPyruvic AcidFermentationLactic Acid FermentationAlcoholic FermentationCitric Acid Cycle(Krebs Cycle)Electron Transport Chain
*Getting Energy to Make ATPC6H12O6 + 6 O2 6CO2 + 6 H2O + ATP
The mitochondria in cells breaks down glucose and produces energy-in this case ATP.
EXERGONIC: Releases energyCATABOLIC: Breaking down molecules
*Cellular Respiration Three stages of cellular respirationGlycolysis - anaerobicThe Citric Acid Cycle (Krebs Cycle) - aerobicThe electron transport chain aerobicThe aerobic phase produces the most ATP
*Overview of Cellular Respiration
*GlycolysisTakes place in the cytoplasm of the cellIt requires no oxygen (anaerobic).Glucose (a 6 carbon molecule) is broken down into 2 molecules of pyruvate (a 3 carbon compound).It requires 2 ATPIt produces 4 ATPA net gain of 2 ATP
*The Krebs CycleTakes place in the mitochondria of the cell (in the matrix).The pyruvate from glycolysis is slightly modified before the citric acid cycle begins.These new molecules are broken down to form ATP and CO2.One ATP per cycle is produced, two cycles occur per glucose molecule therefore 2 ATPs are produced by Krebs Cycle.*Also generates high energy electrons carried by NADH and FADH2.
*Krebs Cycle/Citric Acid Cycle
*The Electron Transport Chain (makes up to 34 ATP)The final stage of respirationTakes place on inner mitochrondrial membrane (cristae)Similar to the events in the light-dependent reactions of photosynthesis.Electrons are passed from protein to protein, and the energy they give off is used to produce more ATPs. The final electron acceptor is an oxygen atom.This is why we cannot live without oxygen!Collects H+ ions and low energy electrons! (waste)CREATES H2O (water)
*Electron Transport Chain
*Where do the electrons come from?Electrons for the ETC come from electron carriers: FADH2 and NADHWork like NADPH (from photosynthesis)Formation of FADH2 and NADH occurs during glycolysis and citric acid cycleGlycolysisNAD+ and H+ combine with e- to make NADHCitric Acid CycleMore NADH formsFAD+ and H+ combine with e- to make FADH2
*RespirationOne glucose molecule is capable of producing a net amount of 36-38 ATP during the entire process of cellular respiration.2 in glycolysis2 from the Krebs Cycle32 to 34 from the electron transport chain
*FermentationWhen oxygen isnt available, the aerobic stages of respiration obviously cant begin.In this situation, fermentation begins after glycolysis as an alternate form of respiration.Why can glycolysis still go on?Fermentation provides small amounts of ATP until the cell can once again obtain enough oxygen to begin the aerobic stages of respiration. **does not last long**
*FermentationTwo main types Alcoholic FermentationCommon in yeast cells. CO2 and alcohol is produced.Example: breadLactic Acid FermentationOccurs in animal muscle cells. Lactic acid is produced.Example: pain in muscles from exercise
*Yeast in BreadYeast is a fungusIt consumes theSugar in the dough-Dough is left to rise-Yeast produces alcohol and CO2 during fermentation-Alcohol evaporates as bread cooks-CO2 makes bubbles holes in bread
*ATP and ExerciseRunningSprinting uses energy:Stored in muscles: runs out quickly; within secondsMade by lactic acid fermentation: (oxygen depleted)made quickly, runs out quickly (about 90 seconds); lactic acid produced = burning sensation in legsExplains why a sprinter breathes very heavily at the end of a raceLong Term EnergyMade by cellular respiration: needs oxygen which is why runners breathe heavilyMakes energy slower than fermentation; runners pace themselvesGlycogen stores last for about 15-20 minutes of activityAfter that, body breaks down fats and other stored molecules for energyAerobic Exercises = help with weight control