CELLULAR CELLULAR RESPIRATIONRESPIRATIONA cell gains useful energyA cell gains useful energy(Oxygen consumed as a reactant along (Oxygen consumed as a reactant along

with organic fuel)with organic fuel) To perform their tasks cells require E To perform their tasks cells require E

from outside sourcesfrom outside sources Harvest energy stored in food with Harvest energy stored in food with

help of enzymeshelp of enzymes The Mitochondria house most of the The Mitochondria house most of the

metabolic equipmentmetabolic equipment

ATP is the central characterATP is the central character ATP regenerates its supply from ADPATP regenerates its supply from ADP Glucose and other organic fuels are Glucose and other organic fuels are

broken down gradually in a series of broken down gradually in a series of steps, each one catalyzed by a steps, each one catalyzed by a coenzymecoenzyme

Coenzyme: small organic non-protein Coenzyme: small organic non-protein molecules that carry chemical groups molecules that carry chemical groups between molecules. Ie……..between molecules. Ie……..

NAD+ => NADHNAD+ => NADHRedox ReactionsRedox Reactions Transfer of electrons or degree of Transfer of electrons or degree of

electron sharing in covalent bondselectron sharing in covalent bonds Loss of electron – OxidationLoss of electron – Oxidation By oxidizing glucose, respiration By oxidizing glucose, respiration

takes energy out of storage and takes energy out of storage and makes it available for ATP synthesismakes it available for ATP synthesis

Electron Transport ChainElectron Transport Chain Consists of several molecules, Consists of several molecules,

mostly proteins built into the inner mostly proteins built into the inner membrane of mitochondrianmembrane of mitochondrian

NADH (top)NADH (top)Oxygen (bottom)Oxygen (bottom)

Converts the chemical energy stored Converts the chemical energy stored in food to a form that can be used in food to a form that can be used to make ATPto make ATP

Cellular Respiration is a Cellular Respiration is a cumulative funcion of metabolic cumulative funcion of metabolic stages:stages:

GlycolsisGlycolsis

Krebes CycleKrebes Cycle

Electron Transport Chain & Electron Transport Chain & Oxidation Oxidation PhosphorylationPhosphorylation

GlycolysisGlycolysis Splitting of sugarSplitting of sugar Breaks down glucose into two Breaks down glucose into two

moleucules of a compound called moleucules of a compound called pyruvatepyruvate

Glucose is a six carbon sugarGlucose is a six carbon sugar Oxidized to 2 pyruvateOxidized to 2 pyruvate Occurs outside the MitochondriaOccurs outside the Mitochondria

No CO2 is released whether or No CO2 is released whether or not oxygen is presentnot oxygen is present

10 steps10 steps Yields 2 ATPYields 2 ATP

..\Illustrations\..\Illustrations\KrebesKrebes Cycle.jpgCycle.jpg

Krebes CycleKrebes Cycle Glycolysis releases less than ¼ of the Glycolysis releases less than ¼ of the

chemical energy stored in Glucosechemical energy stored in Glucose Most remains in the 2 PyruvateMost remains in the 2 Pyruvate If O2 is present, Pyruvates enter the If O2 is present, Pyruvates enter the

MitochondrianMitochondrian First converted to Acetyl CoAFirst converted to Acetyl CoA

junction between Glycolysis and junction between Glycolysis and the the Krebes CycleKrebes Cycle

Catalyzed -----Catalyzed ----- the release of 1 Co2 the release of 1 Co2

8 Steps8 Steps

Step 1Step 1 Acetyl CoA Acetyl CoA 6-carbon citrate 6-carbon citrate

Step 2Step 2 Molecule of water removed then Molecule of water removed then

added back added back Citrate -> Citrate -> IsocitrateIsocitrate

Step 3Step 3 CO2 molecule is lostCO2 molecule is lost Removing 5 carbon compound ie Removing 5 carbon compound ie

oxidizedoxidized Reducing NAD+ to NADHReducing NAD+ to NADH

Step 4Step 4 Catalyzed by a multienzyme complexCatalyzed by a multienzyme complex CO2 is lostCO2 is lost

Remaining 4-carbon compound is oxydized Remaining 4-carbon compound is oxydized the transfer of electron to NAD+ -> NADHthe transfer of electron to NAD+ -> NADH

Then is attached to CoenzymeA by an Then is attached to CoenzymeA by an unstable bondunstable bond

Step 5Step 5 Substrate level phosphorylation (addition Substrate level phosphorylation (addition

of a phosphate group) occurs in the stepof a phosphate group) occurs in the step CoA is displaced & transferred to GDP -> CoA is displaced & transferred to GDP ->

GTPGTP GTP donates a phosphorate group to ADP -GTP donates a phosphorate group to ADP -

> ATP > ATP

Step 6Step 6 Oxidative stepOxidative step 2 hrydrogens are transferred to 2 hrydrogens are transferred to

FAD -> FADH2FAD -> FADH2

Step 7Step 7 Bonds in the substrate are Bonds in the substrate are

rearranged by the addition of a rearranged by the addition of a water moleculewater molecule

Step 8Step 8 Produces another molecule of Produces another molecule of

NADHNADH Prepares Acetyl CoA for another Prepares Acetyl CoA for another

turn in the cycleturn in the cycle

Electron Transport ChainElectron Transport Chain Electrons removed during Electrons removed during

glycolysis and the krebes cycle glycolysis and the krebes cycle are transferred by NADH to the are transferred by NADH to the first molecule of the Electron first molecule of the Electron Transport ChainTransport Chain

Function is to ease electron from Function is to ease electron from food to oxygenfood to oxygen

SO WHAT DOES ALL THIS MEAN?SO WHAT DOES ALL THIS MEAN?Cellular ShockCellular Shock

Inadequate tissue perfusion Inadequate tissue perfusion anaerobic metabolismanaerobic metabolism

Cellular energy source is glucoseCellular energy source is glucose Glycolysis --Glycolysis -- Pyruvic Acid Pyruvic Acid CO2 + CO2 +

H20 the EH20 the E Hypoxia -> Glycolysis -> Pyruvic acid -> Hypoxia -> Glycolysis -> Pyruvic acid ->

lactic acid -> cellular death -> tissue lactic acid -> cellular death -> tissue death -> organ failure -> deathdeath -> organ failure -> death