Ap Bio Ch6 PowerPoint
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Chapter 6Chapter 6
Energy FlowEnergy Flowin Cellsin Cells
Chapter 6 2 The Laws of ThermodynamicsThe Laws of Thermodynamics
First Law of ThermodynamicsFirst Law of Thermodynamics• Energy can neither be created nor destroyedEnergy can neither be created nor destroyed• The total amount of energy within a given The total amount of energy within a given
system remains constant unless energy is system remains constant unless energy is added or removed from the systemadded or removed from the system
The Second Law of ThermodynamicsThe Second Law of Thermodynamics• The amount of useful energy decreases when The amount of useful energy decreases when
energy is converted from one form to anotherenergy is converted from one form to another• EntropyEntropy (disorder) increases (disorder) increases
Chapter 6 3
Chapter 6 4 Energy of SunlightEnergy of Sunlight
Living things must gain external energy Living things must gain external energy in order to counteract the increase in in order to counteract the increase in their entropytheir entropy
• Photosynthetic organisms use external Photosynthetic organisms use external solar energy to maintain orderly solar energy to maintain orderly structurestructure
• Non-photosynthetic organisms use Non-photosynthetic organisms use stored chemical energy in other living stored chemical energy in other living things to counter increasing entropythings to counter increasing entropy
Chapter 6 5
Exergonic ReactionsExergonic Reactions
EnergyEnergycontentcontent
ofofmoleculesmolecules
highhigh
lowlow
(a)(a) Burning glucose (sugar):Burning glucose (sugar):an exergonic reactionan exergonic reaction
Progress of reactionProgress of reaction
Activation energy neededActivation energy neededto ignite glucoseto ignite glucose
Activation energy neededActivation energy neededto ignite glucoseto ignite glucose
Glucose + OGlucose + O22Glucose + OGlucose + O22
Energy released byEnergy released byburning glucoseburning glucose
Energy released byEnergy released byburning glucoseburning glucose
C OC O22 + H + H22OOC OC O22 + H + H22OO
Chapter 6 6
Exergonic ReactionsExergonic Reactions
EnergyReleased
++
++High EnergyHigh EnergyReactantsReactants
Low EnergyLow EnergyProductsProducts
OHO
OCH2OH
O O
O OC
OHH
Chapter 6 7
Endergonic ReactionsEndergonic Reactions
EnergyEnergycontentcontent
ofofmoleculesmolecules
highhigh
lowlow
(b)(b) Photosynthesis:Photosynthesis:an endergonic reactionan endergonic reaction
Progress of reactionProgress of reaction
GlucoseGlucoseGlucoseGlucose
Net energyNet energycaptured bycaptured bysynthesizingsynthesizing
glucoseglucose
COCO22 + H + H22OOCOCO22 + H + H22OO
ActivationActivationenergy fromenergy from
light capturedlight capturedby photosynthesisby photosynthesis
Chapter 6 8
Endergonic ReactionsEndergonic Reactions
++
Low EnergyLow EnergyReactantsReactants ++
High EnergyHigh EnergyProductsProducts
OHO
OCH2OH
O O
O OC
OHH
EnergySupplied
Chapter 6 9
Coupled ReactionsCoupled Reactions
Chapter 6 10
========
Phosphorylation & ATPPhosphorylation & ATP
Chapter 6 11
ATPATP versus versus ADP:ADP:Structural DifferencesStructural Differences
OH
PPO
O
O PP OH
OH
O
~~RiboseRibose
HH22CCHH22CC
HHHH
OOOO
HHHH
OHOHOHOHOHOHOHOH
HHHHHHHH
NNNNHCHCHCHC
NNNN CCCC
CCCC
CCCC
CHCHCHCH
NNNN
NNNN
NHNH22NHNH22
AdenineAdenine
Adenosine
Adenosine
PP OH
OH
O
OH
PPO
O
O PP O
OH
O
~~RiboseRibose
HH22CCHH22CC
HHHH
OOOO
HHHH
OHOHOHOHOHOHOHOH
HHHHHHHH
NNNNHCHCHCHC
NNNN CCCC
CCCC
CCCC
CHCHCHCH
NNNN
NNNN
NHNH22NHNH22
AdenineAdenine
Adenosine
Adenosine
~~
DiPhosphateDiPhosphate
TriPhosphateTriPhosphate
ADPADP
ATPATP
High-energyHigh-energyPhosphatePhosphate
BondBond
Chapter 6 12
Coupled ReactionsCoupled Reactionswithin Living Cellswithin Living Cells
Chapter 6 13
Electron CarriersElectron Carriers
Chapter 6 14
Metabolic PathwaysMetabolic Pathways
AA BB CC DDDD EEEE
FFFF GGGG
Enzyme 1Enzyme 1 Enzyme 2Enzyme 2 Enzyme 3Enzyme 3 Enzyme 4Enzyme 4
Enzyme 5Enzyme 5 Enzyme 6Enzyme 6
InitialInitialReactantsReactants
IntermediatesIntermediates FinalFinalProductsProducts
Pathway 1Pathway 1Pathway 1Pathway 1
Pathway 2Pathway 2Pathway 2Pathway 2
Chapter 6 15
EnergyEnergycontentcontent
ofofmoleculesmolecules
highhigh
lowlowProgress of reactionProgress of reaction
ActivationActivationenergy withoutenergy without
catalystcatalyst
ActivationActivationenergy withenergy with
catalystcatalyst
Activation Energy:Activation Energy:Controls Rate of ReactionControls Rate of Reaction
Chapter 6 16
Enzyme-Substrate InteractionsEnzyme-Substrate InteractionsSubstrateSubstrateSubstrateSubstrateSubstrateSubstrateSubstrateSubstrate
EnzymeEnzymeEnzymeEnzyme
ActiveActiveSiteSite
ActiveActiveSiteSite
11 Substrates Substrates enter active enter active sitesite
11 Substrates Substrates enter active enter active sitesite
22 Shape change Shape change promotes reactionpromotes reaction
22 Shape change Shape change promotes reactionpromotes reaction
33 Product released;Product released;enzyme ready againenzyme ready again
33 Product released;Product released;enzyme ready againenzyme ready again
Chapter 6 17
Enz. 5Enz. 5Enz. 5Enz. 5DDDD
Enz. 4Enz. 4Enz. 4Enz. 4CCCC
Enz. 3Enz. 3Enz. 3Enz. 3BBBB
Enzyme Regulation:Enzyme Regulation:Feedback InhibitionFeedback Inhibition
Enz. 2Enz. 2Enz. 2Enz. 2AAAA
Feedback InhibitionFeedback InhibitionIsoleucine inhibits enzyme 1Isoleucine inhibits enzyme 1
Enz. 1Enz. 1Enz. 1Enz. 1
CHCH33CHCH33
CCCC
CCCC
COOHCOOHCOOHCOOH
OHOHOHOH
NHNH33NHNH33HHHH
HHHHCHCH22
CHCH22
CCCC
CCCC
COOHCOOHCOOHCOOH
CHCH33CHCH33
NHNH33NHNH33HHHH
HHHH
CHCH33CHCH33
ThreonineThreonine(substrate)(substrate)ThreonineThreonine(substrate)(substrate) IsoleucineIsoleucine
(end product)(end product)IsoleucineIsoleucine
(end product)(end product)
Chapter 6 18
Enzyme Regulation: AllostericEnzyme Regulation: AllostericRegulation & Competitive InhibitionRegulation & Competitive Inhibition
SubstrateSubstrateSubstrateSubstrate
EnzymeEnzymeEnzymeEnzyme
Active Active SiteSite
Active Active SiteSite
Allosteric Allosteric Regulatory Regulatory SiteSite
Allosteric Allosteric Regulatory Regulatory SiteSite
(a)(a)
Allosteric Allosteric Regulatory Regulatory
MoleculeMolecule
Allosteric Allosteric Regulatory Regulatory
MoleculeMolecule
Shape of activeShape of activesite changedsite changed(b)(b)
(c)(c)
Competitive inhibitorCompetitive inhibitoroccupies active siteoccupies active site
Chapter 6 19 Environmental ConditionsEnvironmental Conditions
Three-dimensional structure of an enzyme Three-dimensional structure of an enzyme is sensitive to pH, salts, temperature, is sensitive to pH, salts, temperature, and presence of coenzymesand presence of coenzymes
Enzyme structure is distorted and function Enzyme structure is distorted and function is destroyed when pH is too high or lowis destroyed when pH is too high or low
Salts in an enzyme’s environment can also Salts in an enzyme’s environment can also destroy function by altering structuredestroy function by altering structure
Chapter 6 20 Environmental ConditionsEnvironmental Conditions
Temperature also affects enzyme activityTemperature also affects enzyme activity• Low temperatures slow down molecular Low temperatures slow down molecular
movementmovement• High temperatures cause enzyme shape High temperatures cause enzyme shape
to be altered, destroying functionto be altered, destroying function
Most enzymes function optimally only Most enzymes function optimally only within a very narrow range of these within a very narrow range of these conditionsconditions
Chapter 6 21
Chapter 6 22
Chapter 6Chapter 6
The endThe end