CELLULAR RESPIRATION1I. General InfoDefinition: Cellular respiration is the break down of food to get energy (ATP)Enzymes control every step of this processAll living things respireOverall chemical equation:C6H12O6 + 6O2 > 6CO2 + 6H2O + 36 ATP2From Food to ATP
Functions of ATPChemical work supplies energy needed to make macromoleculesTransport work supplies energy to transport substances across the cell membrane. Mechanical work supplies energy to allow muscle contraction, separation of chromosomes etc.
4Respiration PathwaysFood is broken down and energy is released in a three stage process Glycolysis Krebs Cycle Electron Transport Draw Fig. 9-2, pg. 2225Glucose(C6H1206)+Oxygen(02)GlycolysisKrebsCycleElectronTransportChainCarbon Dioxide(CO2)+Water(H2O)Cellular RespirationGlycolysisTakes place in the cytoplasm of a cell.Does not require oxygen.Two ATP molecules are formed.Summary: Glucose (has 6 carbons) is broken down into 2 pyruvic acid molecules (each has 3 carbons)Chemical overview
GlucoseTo the electron transport chain2 Pyruvic acid2 Pyruvic acidDRAW FIG 9-3, pg. 2237Glycolysis means splitting of sugar
What does anaerobic mean?When oxygen is not present, glycolosis is followed by fermentation (2 types)Alcohol FermentationIn yeastCH3CH2OH +Pyruvic AcidEthanolO2 ATP is produced and NADH is converted to NAD+ allowing glycolysis to continueAnaerobic PathwaysCO2 + NAD++ NADHCH3CCOOO9Lactic Acid Fermentation (feel the burn!)Lactic acid is produced in muscles of birds and mammals when the body cant supply enough O2 to tissuesRegenerates NAD+ so glycolysis can continueOxygen debt: the amount of O2 required to convert lactic acid back to pyruvic acid.
GlucosePyruvic acidLactic acidO2GlycolysisLactic Acid FermentationDRAW FIG. 9-4,pg. 22510Prokaryotic organisms produce lactic acid that is used in the production of foods like yogurt, cheese, buttermilk, sour cream, kimchi, pickles and sauerkrat.
MitochondriaDouble membrane organelleCentral cavity known as matrix Inner membrane folds known as cristaeDraw Fig. 9-1, pg 221
Krebs Cycle (Citric Acid Cycle) Requires oxygen.Takes place in the mitochondrial matrix.2 ATP molecules are generated.Pyruvic acid (made during glycolysis) is broken down into CO2 in a series of energy-extracting reactions.High-energy electrons are generated and accepted by electron carriers (NAD+ and FAD)Requires an intermediate step before the cycle can begin14G. Intermediate Step
One C atom from a pyruvic acid molecule becomes part of CO2The other two C atoms combine with CoEnzyme A to form Acetyl-CoEnzymeAThen Acetyl-CoEnzyme A enters the Kreb cycle by combining with a 4-carbon compound to form a 6-carbon compound (citric acid)you are burning carbon and releasing it as carbon dioxide every time you breathe out
Draw Krebs CyclePg. 227Why is it called a cycle? What happens to the high energy electrons carried on FADH2 and NADH?
Electron Transport ChainHigh energy electrons from the Krebs cycle are transported by NADH and FADH2 to the Electron Transport Chain.On the cristae of the mitochondria, electrons are transferred from one carrier protein to another creating energy.This process produces 32 ATP.At the end of the chain an enzyme combines these used up electrons with H+ ions and oxygen to form water.19As high energy electrons fall they lose energy to create ATP. Oxygen has high electron affinity and pull the electrons down to the end of the chain forming water. It is essential as the final electron acceptor combining with H ions and making water
Electron Transport Chain (Fig 9-7, pg. 228)
Electron TransportHydrogen Ion MovementATP ProductionATP synthaseChannelInner MembraneMatrixIntermembrane Space20
The Big Picture
GlucoseGlycolysis Krebs cycle ElectrontransportFermentation (without oxygen)Alcohol or lactic acidC6H12O6+ 6 O2 + 6 CO26 H2OCellular RespirationPhotosynthesis232236 ATP Draw Fig 9-8; pg 229