chapter 6 powerpoint le
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MetabolismChapter 06
2MetabolismMetabolism
OutlineOutline
Forms of EnergyForms of EnergyLaws of ThermodynamicsLaws of Thermodynamics
Metabolic ReactionsMetabolic ReactionsATPATP
Metabolic PathwaysMetabolic PathwaysEnergy of ActivationEnergy of ActivationEnzymesEnzymesPhotosynthesisPhotosynthesisCellular RespirationCellular Respiration
3MetabolismMetabolism
Forms of EnergyForms of Energy
KineticKinetic::
Energy of motionEnergy of motion
MechanicalMechanical
PotentialPotential::
Stored energyStored energy
ChemicalChemical
4Flow of Energy
5MetabolismMetabolism
Laws of ThermodynamicsLaws of Thermodynamics
First law:First law:Law of Law of conservation of energyconservation of energyEnergy cannot be created or destroyed, butEnergy cannot be created or destroyed, butEnergy CAN be changed from one form to Energy CAN be changed from one form to anotheranother
Second law:Second law:Law of Law of entropyentropyWhen energy is changed from one form to When energy is changed from one form to another, there is a loss of usable energyanother, there is a loss of usable energy
Waste energy goes to increase disorderWaste energy goes to increase disorder
6Carbohydrate Synthesis
7Carbohydrate Metabolism
8Cells and Energy
9MetabolismMetabolismMetabolic Reactions andMetabolic Reactions andEnergy TransformationsEnergy Transformations
MetabolismMetabolism::
Sum of cellular chemical reactions in cellSum of cellular chemical reactions in cell
ReactantsReactants participate in reaction participate in reaction
ProductsProducts form as result of reaction form as result of reaction
Free energyFree energy is the amount of energy available is the amount of energy available to perform workto perform work
Exergonic ReactionsExergonic Reactions - Products have - Products have lessless free free energy than reactants energy than reactants
Endergonic ReactionsEndergonic Reactions - Products have - Products have moremore free energy than reactantsfree energy than reactants
10MetabolismMetabolism
ATP and Coupled ReactionsATP and Coupled Reactions
Adenosine triphosphateAdenosine triphosphate ( (ATPATP))High energy compound used to drive High energy compound used to drive metabolic reactionsmetabolic reactions
Constantly being generated from adenosine Constantly being generated from adenosine diphosphate (diphosphate (ADPADP))
Composed of:Composed of:AdenineAdenine and and riboseribose (together = (together = adenosineadenosine), ), andand
Three phosphate groupsThree phosphate groupsCoupled reactionsCoupled reactions
Energy released by an exergonic reaction Energy released by an exergonic reaction captured in ATPcaptured in ATP
That ATP used to drive an endergonic reactionThat ATP used to drive an endergonic reaction
11The ATP Cycle
12Coupled Reactions
Figure 6.4
13MetabolismMetabolismMetabolic Reactions andMetabolic Reactions andEnergy TransformationsEnergy Transformations
MetabolismMetabolism::
Sum of cellular chemical reactions in cellSum of cellular chemical reactions in cell
ReactantsReactants participate in reaction participate in reaction
ProductsProducts form as result of reaction form as result of reaction
Free energyFree energy is the amount of energy available is the amount of energy available to perform workto perform work
Exergonic ReactionsExergonic Reactions - Products have - Products have lessless free free energy than reactants energy than reactants
Endergonic ReactionsEndergonic Reactions - Products have - Products have moremore free energy than reactantsfree energy than reactants
14MetabolismMetabolismWork-Related FunctionsWork-Related Functionsof ATPof ATP
Primarily to perform cellular workPrimarily to perform cellular work
Chemical Work - Energy needed to synthesize Chemical Work - Energy needed to synthesize macromoleculesmacromolecules
Transport Work - Energy needed to pump Transport Work - Energy needed to pump substances across plasma membranesubstances across plasma membrane
Mechanical Work - Energy needed to contract Mechanical Work - Energy needed to contract muscles, beat flagella, etcmuscles, beat flagella, etc
15MetabolismMetabolism
Metabolic PathwaysMetabolic Pathways
Reactions are usually occur in a sequenceReactions are usually occur in a sequenceProducts of an earlier reaction become Products of an earlier reaction become reactants of a later reactionreactants of a later reaction
Such linked reactions form a Such linked reactions form a metabolic metabolic pathwaypathway
Begins with a particular Begins with a particular reactantreactant,,
Proceeds through several Proceeds through several intermediatesintermediates, and, and
Terminates with a particular Terminates with a particular end productend product
AB C D E FG“A” is Initial
Reactant“G” is End
ProductIntermediates
16MetabolismMetabolism
EnzymesEnzymes
EnzymesEnzymesProtein molecules that function as catalystsProtein molecules that function as catalystsThe reactants of an enzymatically accelerated The reactants of an enzymatically accelerated reaction are called reaction are called substratessubstrates
Each enzyme accelerates a specific reactionEach enzyme accelerates a specific reactionEach reaction in a metabolic pathway requires Each reaction in a metabolic pathway requires a unique and specific enzymea unique and specific enzyme
End product will not appear unless ALL End product will not appear unless ALL enzymes present and functionalenzymes present and functional
E1 E2 E3 E4 E5 E6A B C D E F G
17MetabolismMetabolismEnzymes:Enzymes:Energy of ActivationEnergy of Activation
Reactants often “reluctant” to participate in Reactants often “reluctant” to participate in reactionreaction
Energy must be added to at least one reactant Energy must be added to at least one reactant to initiate the reactionto initiate the reaction
Energy of activationEnergy of activation
Enzyme Operation:Enzyme Operation:
Enzymes operate by lowering the energy of Enzymes operate by lowering the energy of activationactivation
Accomplished by bringing the substrates into Accomplished by bringing the substrates into contact with one anothercontact with one another
18Energy of Activation
19MetabolismMetabolism
Enzyme-Substrate ComplexEnzyme-Substrate Complex
The The active siteactive site complexes with the substrates complexes with the substrates
Causes active site to change shapeCauses active site to change shape
Shape change forces substrates together, Shape change forces substrates together, initiating bondinitiating bond
Induced fit modelInduced fit model
20Induced Fit Model
21MetabolismMetabolism
Degradation vs. SynthesisDegradation vs. Synthesis
DegradationDegradation::
Enzyme complexes with a single substrate Enzyme complexes with a single substrate moleculemolecule
Substrate is broken apart into two product Substrate is broken apart into two product moleculesmolecules
SynthesisSynthesis::
Enzyme complexes with two substrate Enzyme complexes with two substrate moleculesmolecules
Substrates are joined together and released Substrates are joined together and released as single product moleculeas single product molecule
22Degradation vs. Synthesis
23MetabolismMetabolism
Factors Affecting Enzyme Activity (1)Factors Affecting Enzyme Activity (1)
Substrate concentrationSubstrate concentrationEnzyme activity increases with substrate Enzyme activity increases with substrate concentrationconcentration
More collisions between substrate molecules More collisions between substrate molecules and the enzymeand the enzyme
TemperatureTemperatureEnzyme activity increases with temperatureEnzyme activity increases with temperatureWarmer temperatures cause more effective Warmer temperatures cause more effective collisions between enzyme and substratecollisions between enzyme and substrate
However, hot temperatures destroy enzymeHowever, hot temperatures destroy enzymepHpH
Most enzymes are optimized for a particular Most enzymes are optimized for a particular pHpH
24Factors Affecting Enzyme Activity:Temperature
25Factors Affecting Enzyme Activity:pH
26MetabolismMetabolism
Factors Affecting Enzyme Activity (2)Factors Affecting Enzyme Activity (2)
Cells can affect presence/absence of enzymeCells can affect presence/absence of enzyme
Cells can affect concentration of enzymeCells can affect concentration of enzyme
Cells can activate or deactivate enzymeCells can activate or deactivate enzyme
Enzyme Enzyme CofactorsCofactors
Molecules required to activate enzymeMolecules required to activate enzyme
CoenzymesCoenzymes are organic cofactors, like some are organic cofactors, like some vitaminsvitamins
PhosphorylationPhosphorylation – some require addition of a – some require addition of a phosphatephosphate
27Factors Affecting Enzyme Activity:Activation by Phosphorylation
28MetabolismMetabolism
Factors Affecting Enzyme Activity (3)Factors Affecting Enzyme Activity (3)
Reversible Reversible enzyme inhibitionenzyme inhibition
When a substance known as an inhibitor binds to an enzyme and decreases its activity
Competitive inhibitioninhibition – substrate and the – substrate and the inhibitor are both able to bind to inhibitor are both able to bind to active siteactive site
Noncompetitive inhibitionNoncompetitive inhibition – the inhibitor binds – the inhibitor binds not at the active site, but at the not at the active site, but at the allosteric siteallosteric site
Feedback inhibitionFeedback inhibition – The end product of a – The end product of a pathway inhibits the pathway’s first enzymepathway inhibits the pathway’s first enzyme
29Factors Affecting Enzyme Activity:Feedback Inhibition
30MetabolismMetabolism
Irreversible InhibitionIrreversible Inhibition
Materials that irreversibly inhibit an enzyme Materials that irreversibly inhibit an enzyme are known as are known as poisonspoisons
CyanidesCyanides inhibit enzymes resulting in all ATP inhibit enzymes resulting in all ATP productionproduction
PenicillinPenicillin inhibits an enzyme unique to certain inhibits an enzyme unique to certain bacteriabacteria
Heavy metalsHeavy metals irreversibly bind with many irreversibly bind with many enzymesenzymes
Nerve gasNerve gas irreversibly inhibits enzymes irreversibly inhibits enzymes required by nervous systemrequired by nervous system
31MetabolismMetabolism
Oxidation-ReductionOxidation-Reduction
Oxidation-reductionOxidation-reduction ( (redoxredox)) reactions: reactions:
Electrons pass from one molecule to anotherElectrons pass from one molecule to another
The molecule that loses an electron is The molecule that loses an electron is oxidizedoxidized
The molecule that gains an electron is The molecule that gains an electron is reducedreduced
Both take place at same timeBoth take place at same time
One molecule accepts the electron given up One molecule accepts the electron given up by the otherby the other
32Photosynthesis andPhotosynthesis andCellular RespirationCellular Respiration
Carbon dioxideCarbon dioxide+water+water+solar energy+solar energy
GlucoseGlucose+oxygen+oxygen
6CO6CO22 + 6H + 6H22OOenergyenergy
CC66HH1212OO66 + 6O + 6O22
Carbon dioxideCarbon dioxide+water+water+chemical energy+chemical energy
GlucoseGlucose+oxygen+oxygen
6CO6CO22 + 6H + 6H22OOCC66HH1212OO66 + 6O + 6O22
Cellular Respiration:Cellular Respiration:
Photosynthesis:Photosynthesis:
33MetabolismMetabolism
Electron Transport ChainElectron Transport Chain
Membrane-bound carrier proteins found in Membrane-bound carrier proteins found in mitochondria and chloroplastsmitochondria and chloroplasts
Physically arranged in an ordered seriesPhysically arranged in an ordered series Starts with high-energy electrons and low-energy Starts with high-energy electrons and low-energy
ADPADP
Pass electrons from one carrier to anotherPass electrons from one carrier to another
Electron energy used to pump hydrogen ions (HElectron energy used to pump hydrogen ions (H++) to ) to one side of membraneone side of membrane
Establishes electrical gradient across membraneEstablishes electrical gradient across membrane
Electrical gradient used to make ATP from ADP – Electrical gradient used to make ATP from ADP – ChemiosmosisChemiosmosis
Ends with low-energy electrons and high-energy ATPEnds with low-energy electrons and high-energy ATP
34A Metaphor for theElectron Transport Chain
35Chemiosmosis
36MetabolismMetabolism
ReviewReview
Forms of EnergyForms of EnergyLaws of ThermodynamicsLaws of Thermodynamics
Metabolic ReactionsMetabolic ReactionsATPATP
Metabolic PathwaysMetabolic PathwaysEnergy of ActivationEnergy of Activation
EnzymesEnzymes
PhotosynthesisPhotosynthesis
Cellular RespirationCellular Respiration
MetabolismEnding Slide Chapter 06