1 BCOR 011 Lecture 11 BCOR 011 Lecture 11 Chapter 8 Chapter 8 The Flow of Energy in a Cell The Flow of Energy in a Cell Sept 26, 2005 Sept 26, 2005 Figure 8.1 2 Potential Energy Kinetic Energy -stored in height -stored in battery (conc/charge) -stored in BONDS -energy of movement -molecules colliding, vibratin -HEAT, light Energy: the capacity to effect Energy: the capacity to effect change change Two types of energy Two types of energy 3 Potential Energy Stored in: Potential Energy Stored in: On the platform, a diver has more potential energy. Diving converts potential energy to kinetic energy. imbing up converts kinetic ergy of muscle movement In the water, a diver has less potential energy. Figure 8.2 Figure 8.5 location location gradient gradient Chemical Chemical bonds bonds 4 1st Law of Thermodynamics 1st Law of Thermodynamics Energy is neither created nor destroyed in chemical reactions but only Transformed from one form to another Potential Potential Kinetic Kinetic
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The Flow of Energy in a Cell Potential Energy Kinetic …dstratto/bcor011_handouts/Vayda_lecture_notes/11...Electrical work – movement of ... – Convert energy to light, as in bioluminescence
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3. Electrical work 3. Electrical work –– movement of ions acrossmovement of ions acrossa membrane against an electrochemical gradienta membrane against an electrochemical gradient
• Some organisms – Convert energy to light, as in bioluminescence
Figure 8.1
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Energy that is released:Energy that is released:
Has the capacity to Has the capacity to DO WORKDO WORK
Raise potential state of something elseRaise potential state of something else
Or effect movement Or effect movement –– heat, motionheat, motion
But some is always lost to disorderBut some is always lost to disorder16
ChangeChangeIn potentialIn potentialEnergyEnergy
Released EnergyReleased Energy
State 1State 1
State 2State 2
AbilityAbilityTo doTo doworkwork
++ RandomnessRandomness
Gross PayGross PayTake Take HomeHomePayPay
++ TaxesTaxes
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Kinetic Energy can be dissipated: Randomized
Kinetic EnergySoundFloor Vibration
Chance of going in REVERSE?
Releases Energy
RequiresEnergy Input
Disorder
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Only time this is not trueOnly time this is not trueis when no movement anymoreis when no movement anymore
ieie. at . at abosoluteabosolute zerozero
Second law of Thermodynamics:Second law of Thermodynamics:
The Universe is proceeding to a The Universe is proceeding to a State of MAXIMUM DISORDERState of MAXIMUM DISORDER
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00oo KK -- no motion, no “taxes”no motion, no “taxes”
A Progressive Scale:A Progressive Scale:Higher the temperature,Higher the temperature,
the more that disorder comes into playthe more that disorder comes into playhigher proportion of energy lost to randomnesshigher proportion of energy lost to randomness
On On TemperatureTemperatureKinetic MovementKinetic Movement
∆∆G G = = ∆∆H H -- TT∆∆SSIf If ∆∆G = negative # G = negative # reaction is energetically favorable reaction is energetically favorable
““spontaneous”spontaneous”
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∆∆GG = = ∆∆HH –– TT∆∆SS-- ∆∆G is G is favorablefavorable exergonicexergonic “spontaneous”“spontaneous”++ ∆∆G is G is NOT favorable,NOT favorable, endergonicendergonic, , nonspontaneousnonspontaneous 28
An exergonic reaction– Proceeds with a net release of free energy and is spontaneous
Figure 8.6
Reactants
Products
Energy
Progress of the reaction
Amount ofenergyreleased (∆G <0)
Free
ene
rgy
(a) Exergonic reaction: free energy released
““will happen”will happen”
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An An endergonicendergonic reactionreaction–– Is one that Is one that absorbs free energyabsorbs free energy from its from its
surroundings and is surroundings and is nonspontaneousnonspontaneous
Figure 8.6
Energy
Products
Amount ofenergyreleased (∆G>0)
Reactants
Progress of the reaction
Free
ene
rgy
(b) Endergonic reaction: energy required
““doesn’t happen”doesn’t happen”
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2 Factors Contribute to Whether a Reaction will Occur:
change in Bond Energy change in EntropyReduced
Oxidized
Complex
Simple
Net Useful Energy (Net Useful Energy (∆∆G)G)The sum of these is the
If net ENERGY RELEASED - EXERGONIC = FAVORABLE
If require net ENERGY INPUT - ENDERGONIC = UNFAVORABLE
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Complex Simple
Reduced (no oxygens)
Oxidized
High
Lowest
H-C-C-C-C-C-C-C-C-HH
H H
H HHH
HH H H
H
H
H H
H H-C-HH
H
O=C=O
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R-C-OHH
H
Lower
R-C-H
=O
R-C-OH=O
hydrocarbon
alcohol
aldehyde
acidchan
ge in
Bon
d En
ergy
change in Entropy
Low
fats
sugars
Finalproduct
Carbon dioxide 32
EXERGONIC REACTIONSgasoline burnsiron rustshydrogen and oxygen form water (explosive!)
Either: go to bonding arrangement with lower potential energy
Or: go from a more complex state to a simpler state
1 molecule of 8 carbons vs 8 molecules of 1 carbon
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∆∆H=H=∆∆S=S=∆∆G=G=
--++
veryvery --
SpontaneousSpontaneousFavorableFavorable -- it it cancan happen happen
DO NOT LET ATP FALL APART IN 1 STEP, use energy in its bond to MAKE the polymer linkage
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Another Example of a Coupled Reaction
Endergonic reaction: ∆G is positive, reaction is not spontaneous
∆G = +3.4 kcal/molGlu Glu
∆G = + 7.3 kcal/molATP H2O+
+ NH3
ADP +
NH2
Glutamicacid
Ammonia Glutamine
Exergonic reaction: ∆ G is negative, reaction is spontaneous
P
Coupled reactions: Overall ∆G is negative;together, reactions are spontaneous ∆G = –3.9 kcal/molFigure 8.10
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Three types of cellular work powered by Three types of cellular work powered by ATP hydrolysisATP hydrolysis
(c) Chemical work: ATP phosphorylates key reactants
P
Membraneprotein
Motor protein
P i
Protein moved(a) Mechanical work: ATP phosphorylates motor proteins
ATP
(b) Transport work: ATP phosphorylates transport proteins
Solute
P P i
transportedSolute
GluGlu
NH3
NH2
P i
P i
+ +
Reactants: Glutamic acid and ammonia
Product (glutamine)made
ADP+
P
Figure 8.11
BiosyntheticBiosyntheticCoupledCoupled
RxnRxn
DrivingDrivingConformationalConformational
ChangesChangesOf Of
ProteinsProteins
PhysicalPhysicalmovementmovement
ActiveActiveTransportTransport
PumpsPumps
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EquilibriumReactions in a closed system
– Eventually reach equilibrium
Figure 8.7 A
(a) A closed hydroelectric system. Water flowing downhill turns a turbine that drives a generator providing electricity to a light bulb, but only until the system reaches equilibrium.
∆G < 0 ∆G = 0
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In living systems– Experience a constant flow of materials in – Constant Energy Input
Figure 8.7
(b) An open hydroelectric system. Flowing water
keeps driving the generator because intake and outflow of water keep the system
from reaching equlibrium.
∆G < 0
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cellular respiration is a series of favorable reactions
Figure 8.7 (c) A multistep open hydroelectric system. Cellular respiration is
analogous to this system: Glucoce is brocken down in a seriesof exergonic reactions that power the work of the cell. The productof each reaction becomes the reactant for the next, so no reaction reaches equilibrium.
∆G < 0
∆G < 0
∆G < 0
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For example, oxidation of glucose:C6H12O6 (glucose) + 6O2 6CO2 + 6H2O
∆G= -686 kcal/mol ∆H = -673 kcal/mol
T∆S= -13 kcal/mol
in the cell, this is done in >21 steps!
Capture the energy in small packetsCapture the energy in small packetsieie, 36 ATP units of 7.3 kcal, 36 ATP units of 7.3 kcal
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Summary:Summary:--matter is neither created nor destroyedmatter is neither created nor destroyed--the universe is proceeding toward disorderthe universe is proceeding toward disorder