Define cellular respiration  Cell respiration is the controlled release of energy from organic compounds in cells to form ATP  Covalent bonds are slowly

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    13-Jan-2016

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  • Define cellular respirationCell respiration is the controlled release of energy from organic compounds in cells to form ATPCovalent bonds are slowly oxidized by enzymes releasing ATP moleculesTakes place in the presence or in absence of oxygen

  • Know These Numbers

  • Glycolysisglucose + 2 ATP 2 pyruvate + 4 ATP + 2 NADPHThe breakdown of one molecule of glucose into two molecules of pyruvate with the release of some energyTakes place in the cytoplasmDoes not require oxygenGlycolysis Video

  • Alcoholic FermentationDone when no oxygen is presentStarts with glycolysisThe pyruvate is then broken down furtherYeast turn the pyruvate into ethanol and carbon dioxideUsed to make bread and alcohol

  • Lactic Acid FermentationCell that normally do aerobic respiration can perform fermentationDone when you sprint and the body can not supply the muscles with enough oxygen to perform aerobic respirationCan cause muscle cramps

  • Aerobic cellular respirationIn the presence of oxygen pyruvate is broken down in the mitochondria into carbon dioxide and waterThis is the most efficient use of this molecule to harvest energyReaction takes place in the mitochondriaYields approximately 28-34 more ATP

  • Oxidation and ReductionRedox (reduction oxidation) reaction: the enzyme controlled transfer of electronsOxidation Is the Loss of electronsInvolves gaining an oxygen or losing a hydrogenEnergy is lost (exergonic reaction)In respiration glucose is oxidised to carbon dioxideAll hydrogens are gradually removed from the glucose moleculeReduction Is the Gain of electronsInvolves losing oxygen or gaining hydrogenEnergy is absorbed (endergonic reaction)This substance now has the power to reduce other substances and become oxidised in the processIn respiration oxygen is reduced to waterRemember it by the saying OIL RIG

  • OxidationReductionLoss of electronsGain of electronsGain of oxygenLoss of oxygenLoss of hydrogenGain of hydrogenResults in many C-O bondsResults in many C-H bondsResult is a compound with low potential (stored) energyResult is compound with high potential (stored) energy

  • GlycolysisLinear series of reactions in which glucose is broken down into 2 molecules of pyruvateGlycolysis takes place in the cytoplasmGlucose + 2ADP + 2Pi + 2NAD+ 2Pyruvate + 2ATP + 2NADH + 2H+ + 2H20Anaerobic process that does not require oxygenGlycolysis takes a 6-carbon hexose sugar and created 2 3-carbon monosaccharidesThe first step is phosphorylationATP is used to add a phosphate group to the glucoseA second phosphorylation using another ATP follows adding a second phosphateThis creates fructose biphosphate2 molecules of ATP are consumed for every molecule of glucose at this point

  • Glycolysis Cont.The second step is lysisFructose biphosphate is split producing 2 triose phosphate molecules each with 3 carbonsThe third step is oxidationThe above chemicals are then involved in a combined oxidation phosphorylation reactionHydrogen is removed from the triose phosphatesNAD acts as the hydrogen receptorThe last step is ATP formationLastly the triose biphosphate gives up one of the phosphates to ADP to make it ATP and producing pyruvateTotal ATP production for each glucose molecule is 4 but the NET gain is only 2Remember we spent 2 ATP at the beginning to start the process

  • Electron Micrograph of a Mitochondria

  • Micrograph ExplainedFound in the cytoplasm of all Eukaryotic cells, usually in large numbersLarge organelle surrounded by an outer membrane and an inner membraneInner membrane is folded cristaeBetween the inner membrane and the outer membrane is the matrixInside is a watery fluid containing enzymes and moleculesThere are also ribosomes and DNAThe DNA is maternal DNA and can be used to trace heredity

  • Structure and Function

    StructureFunction / RoleExternal Double MembranePermeable to pyruvate, CO2, O2 and NAD/NADHMatrixSite of enzymes of link reaction and Krebs cycleInner MembraneSurface area greatly increased by in tucking to form cristae (increases surface area for electron chain), impermeable to hydrogen ions (allows for a concentration gradient to be created

    Inter-membrane SpaceRelatively tiny space, allows the accumulation of hydrogen atoms , facilitates phosphorylation

  • Aerobic Respiration Link ReactionForms the link between glycolysis and the Krebs cyclePyruvate is transferred from the cytoplasm to the mitochondrial matrixPyruvate + CoA + NAD+ Acetyl CoA + CO2 + NADH + H+This reaction is known as decaboxylation of pyruvateA carbon dioxide is removedThe molecule is also oxidised by the removal of a hydrogenNAD is formed at this time

  • Aerobic RespirationKrebs CycleAlso known as tricarboxylic citric acid cycle or TCA cycleOccurs in the matrix of the mitochondria1 molecule of acetyl CoA yields 2 CO2 3 NADH + 3H+1 FADH21 ATP

  • Krebs Cycle DetailsAcetyl CoA combines with a 4-carbon compound to create a 6-carbon compoundThis compound is then decarboxylatedA CO2 is removed 5-carbon compound is createdThe 5-carbon compound is decarboxylatedA CO2 is removed 4-carbon compound is createdThis takes us back the original 4-carbon compound that starts the cycleThe main outputs are energy freed from the compounds

  • Krebs Cycle Important Notesper molecule that entersTwo molecules of carbon dioxide are given off in separate decaboxylation reactionsOne molecule of ATP is formedThree molecules of NADH (aka reduced NAD) are formedOne molecule of FADH (aka reduced FAD) is formed

  • Summary to this Point

    StepCO2ATPNADHFADHGlycolysis0220Link Reaction2020Krebs Cycle4262Totals6 CO24 ATP10 NADH2 FADH

  • Terminal Oxidation and oxidative phosphorylation

    A.K.A. the electron transport chainThe removal of H+ from NADH and FADHReleases energy that is transferred to ADP to form ATPEnd receiver of the H+ is O2 and this forms waterFor every molecule of NADH that is reduced 3 ATP are formedTotal yield from aerobic respiration is 38 ATPs

  • Phosphorylation by ChemiosmosisThe synthesis of ATP is coupled to electron transport via the movement of protonsElectron carrier proteins are arranged in the inner mitochondrial membrane Oxidize the reduced coenzymesEnergy from the oxidation is used to pump hydrogen ions from the matrix into the space between the inner and outer membranes of the mitochondriaA gradient forms generating a potential difference across the membrane a store of potential energyHydrogens flow back across the membrane through ATP synthesis enzymes (ATPase) Follow the concentration gradient from high hydrogen to low hydrogenEnergy is transferred to ATP

  • Role in Fat MetabolismYour body can plug other things into the Krebs cycle to generate energy includingStarchGlycerolFatty acidsAmino acidsPlants can also add cellulose to this listExplains why fats are considered to be energy sources to the body

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