AP Biology lecture

1. Energy, ATP, and EnzymesEnergy, ATP, and Enzymes
CH. 6CH. 6

2. Ch. 8
1. Energy
1. Types, laws, conversions
2. Chemical reactions
1. Endergonic, exergonic
3. ATP
1. Source of energy for cells
4. Enzymes
1. Speed up chemical reactions
2. Lower activation energy

3. EnergyEnergy

4. Energy is...Energy is...
 The ability toThe ability to do workdo work
 The ability toThe ability to transfertransfer
heatheat
 Forms of EnergyForms of Energy
 Chemical energyChemical energy
 Nuclear energyNuclear energy
 Solar energySolar energy
 Heat energyHeat energy
 Mechanical and ElectricalMechanical and Electrical

5. Measuring EnergyMeasuring Energy
 Two units commonly usedTwo units commonly used::
 CaloriesCalories (C):(C):
Amount of energy it takes to raiseAmount of energy it takes to raise
one gram of water 1one gram of water 1oo
CC
Calories inCalories in foodfood (C) are actually(C) are actually
kilocalories(kilocalories(kcalkcal) =) = 1000 calories1000 calories
 JoulesJoules (J): 4.18 Joules = 1(J): 4.18 Joules = 1
caloriecalorie
So they are
actually 100,000
calorie packs!

6.  Energy due to positionEnergy due to position --
gravitational, electrical,gravitational, electrical,
or in chemical bondsor in chemical bonds
(called chemical energy)(called chemical energy)
 StoredStored energyenergy
Potential EnergyPotential Energy

7.  PositionPosition: boulder at the: boulder at the
top of the hill, watertop of the hill, water
behind a dam, stick ofbehind a dam, stick of
plastiqueplastique
 ChemicalChemical: tank of gas,: tank of gas,
hamburgerhamburger
Potential EnergyPotential Energy

8. Kinetic EnergyKinetic Energy
 Energy due toEnergy due to motion or actionmotion or action
 Electromagnetic waves (light), heat,Electromagnetic waves (light), heat,
motion, electrical currentmotion, electrical current

11. Heat and TemperatureHeat and Temperature
 Heat - thermal energyHeat - thermal energy ==
kinetic energykinetic energy
from the movement of atoms orfrom the movement of atoms or
moleculesmolecules
 TemperatureTemperature ==
average speed of atomsaverage speed of atoms

12. Thermodynamics: the Study ofThermodynamics: the Study of
Energy TransformationsEnergy Transformations

13. 1st Law of Thermodynamics1st Law of Thermodynamics
 Energy cannotEnergy cannot
be created norbe created nor
destroyeddestroyed
 MayMay changechange fromfrom
one form to anotherone form to another
 This is known asThis is known as
thethe law oflaw of
conservation ofconservation of
energyenergy

14. 2nd Law of Thermodynamics2nd Law of Thermodynamics
 Energy transfer is not 100% efficientEnergy transfer is not 100% efficient
and each energy transfer increasesand each energy transfer increases
the entropy of the universethe entropy of the universe
No reaction is 100% efficient
Energy Available To Do Work Decreases Over Time
All reactions lose energy in the form of heat
Heat is a less ordered form of energy than other forms like
chemical or mechanical energy
This increases entropy

15. Transfer of EnergyTransfer of Energy

16. Transfer of EnergyTransfer of Energy
 Running, photosynthesis, eatingRunning, photosynthesis, eating
Chemical to mechanical
Light to
chemical

17. Entropy is...Entropy is...
 TheThe amount of disorderamount of disorder in a systemin a system
 Entropy alwaysEntropy always increases over timeincreases over time (in(in
absence of an input of outside energy)absence of an input of outside energy)
 CleaningCleaning
up your room ...up your room ...

18.  Energy isEnergy is lostlost inin eacheach transformationtransformation
EntropyEntropy

19. Quick Quick ThinksQuick Quick Thinks
 What is the difference between heatWhat is the difference between heat
and temperature?and temperature?
 What are the first and second laws ofWhat are the first and second laws of
thermodynamics?thermodynamics?
 Why is no reaction 100% efficient?Why is no reaction 100% efficient?
(where does the energy go?)(where does the energy go?)

20. Quick ThinkQuick Think
What is the relationshipWhat is the relationship
between energy andbetween energy and
work?work?

21. Challenging Quick ThinkChallenging Quick Think
 How does the 2How does the 2ndnd
law oflaw of
thermodynamicsthermodynamics
help explain thehelp explain the
diffusion of adiffusion of a
substance acrosssubstance across
the cell membrane?the cell membrane?

22. Challenging Quick ThinksChallenging Quick Thinks
Describe the forms ofDescribe the forms of
energy found in an appleenergy found in an apple
as it grows on a tree, thenas it grows on a tree, then
falls and is digested byfalls and is digested by
someone who eats it.someone who eats it.

23. My understanding of energy
is…0 - even with prompting, I can’t show my knowledge
1 - with prompting, I can show knowledge
2 - I get the basics
3 - I understand beyond the basics without help
4 - I can apply my knowledge to homework or test
questions
Knowing that this content is essential to
understanding future content, my next step is to…

24. Chemical ReactionsChemical Reactions

25. Chemical ReactionsChemical Reactions
involves...involves...
 Breaking bonds in reactantsBreaking bonds in reactants
 Forming new ones to create productsForming new ones to create products
 EnergyEnergy is required in one direction andis required in one direction and
given off in anothergiven off in another

26. Energy is required in one direction and givenEnergy is required in one direction and given
off in anotheroff in another
Change of StateChange of State

27. Important Vocab
ENERGY OUT
 Exergonic – energy
releasing
 Cataboloic –
breakdown reaction
 Exothermic – heat
releasing
ENERGY IN
 Endergonic –
energy requiring
 Anaboloic –
building reactions
 Endothermic – heat
absorbing

28. ReactionsReactions
 Gibb’s FreeGibb’s Free
energy (G)energy (G) –– aa
measure of the "useful"measure of the "useful"
energy that can do workenergy that can do work
in a systemin a system
 Think of it as “available”Think of it as “available”
energyenergy
Josiah
Willard
Gibbs

29. ReactionsReactions
 Free energy – systems with high G are less stableFree energy – systems with high G are less stable
are more likely to changeare more likely to change
 Systems with low G are more stable and less likely toSystems with low G are more stable and less likely to
changechange

30. ReactionsReactions
 During chemicalDuring chemical
reactions therereactions there
will be a changewill be a change
in the freein the free
energyenergy
ΔΔGG

31. ReactionsReactions
 ΔΔG = GG = G final statefinal state – G– G initial stateinitial state

32. ReactionsReactions
 WhenWhen ΔΔGG is negative, theis negative, the
reaction will occur spontaneouslyreaction will occur spontaneously
 Reactions that have aReactions that have a ΔΔGG valuevalue
or zero or more are neveror zero or more are never
spontaneousspontaneous
--ΔG =ΔG =
spontaneousspontaneous
+ΔG = not+ΔG = not
spontaneousspontaneous

33. Exergonic
Reactions
Endergonic
Reactions

34. ReactionsReactions
 If we know whatIf we know what
reactions have areactions have a
negative delta G,negative delta G,
we can determinewe can determine
which reactions willwhich reactions will
release energy thatrelease energy that
can be used to docan be used to do
work in the cellwork in the cell Exocytosis – workExocytosis – work
for the cellfor the cell
(requires energy)(requires energy)

35.  Most reactions areMost reactions are
reversiblereversible
 Reversible reactions willReversible reactions will
approachapproach dynamicdynamic
equilibriumequilibrium
 Reactions that come toReactions that come to
equilibrium can no longerequilibrium can no longer
perform workperform work
 They have maximumThey have maximum
stability and low Gstability and low G
ReactionsReactions

36. MetabolismMetabolism
 AllAll thethe
chemicalchemical
reactionsreactions
thatthat
happen inhappen in
anan
organismorganism
metabolismmetabolism
concept mapconcept map

37. ReactionsReactions
 If the reactions ofIf the reactions of
metabolism reachmetabolism reach
equilibrium, a cell couldequilibrium, a cell could
no longer do workno longer do work
 The constant flow ofThe constant flow of
materials into and out ofmaterials into and out of
the cell prevent the cellthe cell prevent the cell
from ever reachingfrom ever reaching
equilibriumequilibrium

38. The more negativeThe more negative ΔΔG is, the more workG is, the more work
that reaction can perform for the cellthat reaction can perform for the cell
CC66HH1212OO66 + 6O+ 6O22 6CO6CO22 + 6H+ 6H22OO
ΔΔG = -686 kcal/molG = -686 kcal/mol

39.  The more positiveThe more positive ΔΔG is, the more energy isG is, the more energy is
required to drive that reactionrequired to drive that reaction
 6CO6CO22 + 6H+ 6H22 0 C0 C66 HH1212 OO66 + 6O+ 6O22
 ΔΔG = +686 kcal/molG = +686 kcal/mol

40. Sources of Free Energy for livingSources of Free Energy for living
thingsthings
 Sun is ultimate source of energy for mostSun is ultimate source of energy for most
ecosystems!ecosystems!
 PhotosynthesisPhotosynthesis
 Organic molecules like glucoseOrganic molecules like glucose
 6CO6CO22 +12H+12H22O+Sun ---->CO+Sun ---->C66HH12120066 + 6H+ 6H22O + 6OO + 6O22

42. Quick ThinkQuick Think
 Cellular respiration uses glucose, whichCellular respiration uses glucose, which
has a high level of free energy, andhas a high level of free energy, and
releases COreleases CO22 and water, which have lowand water, which have low
levels of free energy.levels of free energy.
 Is respiration spontaneous or not?Is respiration spontaneous or not?
 Is it exergonic or endergonic?Is it exergonic or endergonic?
 What happens to the energy releasedWhat happens to the energy released
from glucose?from glucose?

43. Which of the following correctlyWhich of the following correctly
states the relationship between anabolicstates the relationship between anabolic
and catabolic pathways?and catabolic pathways?
A.A. Degradation of organic molecules by anabolic pathways providesDegradation of organic molecules by anabolic pathways provides
the energy to drive catabolic pathways.the energy to drive catabolic pathways.
B.B. Energy derived from catabolic pathways is used to drive theEnergy derived from catabolic pathways is used to drive the
breakdown of organic molecules in anabolic pathways.breakdown of organic molecules in anabolic pathways.
C.C. Anabolic pathways synthesize more complex organic moleculesAnabolic pathways synthesize more complex organic molecules
using the energy derived from catabolic pathways.using the energy derived from catabolic pathways.
D.D. Catabolic pathways produce usable cellular energy byCatabolic pathways produce usable cellular energy by
synthesizing more complex organic molecules.synthesizing more complex organic molecules.
E.E. The flow of energy between catabolic and anabolic pathways isThe flow of energy between catabolic and anabolic pathways is
reversible.reversible.
The answer is ___ because________________
The answer is not ___ because________________

44. Which of the following reactionsWhich of the following reactions
would be endergonic?would be endergonic?
A.A. HClHCl  HH++
+ Cl+ Cl--
B.B. CC66HH1212OO66 + 6 O+ 6 O22  6 CO6 CO22 + 6 H+ 6 H22OO
C.C. ATPATP  ADP + PADP + Pii
D.D. glucose + fructoseglucose + fructose  sucrosesucrose
E.E. all of the aboveall of the above
The answer is ___ because________________
The answer is not ___ because________________

45. Today you learned about
energy
 Create an acrostic for the wordCreate an acrostic for the word
ENERGYENERGY
E - Entropy - which is the…E - Entropy - which is the…
NN
EE
RR
GG
YY

46. ATPATP

47. Cells need energy to do workCells need energy to do work
 Cells do 3 main kinds of work:Cells do 3 main kinds of work:
 MechanicalMechanical – contraction, movement– contraction, movement
 TransportTransport – movement of substances– movement of substances
against the concentration gradientagainst the concentration gradient
 ChemicalChemical – synthesis of polymers from– synthesis of polymers from
monomersmonomers

48. ATP provides the energy for cell workATP provides the energy for cell work
 Before cells can use the energy of sunlight orBefore cells can use the energy of sunlight or
that stored in carbohydrates, they mustthat stored in carbohydrates, they must
transfer the energytransfer the energy to molecules of ATPto molecules of ATP
 ATP powers the cell by using the energy fromATP powers the cell by using the energy from
exergonic reactions to drive endergonicexergonic reactions to drive endergonic
reactionsreactions

49. What is ATP?What is ATP?
 Adenosine triphosphate – aAdenosine triphosphate – a
nucleotidenucleotide
 Composed of adenine, ribose, and threeComposed of adenine, ribose, and three
phosphate groupsphosphate groups
 Cell's chief energy source forCell's chief energy source for
cellular work.cellular work.

50. ATP structureATP structure
 BondsBonds betweenbetween
phosphate groupsphosphate groups
can becan be brokenbroken offoff byby
hydrolysishydrolysis
 This is an exergonicThis is an exergonic
reaction and releasesreaction and releases
7.3 kcal of7.3 kcal of
energy/mole of ATPenergy/mole of ATP
 This is a bit more energyThis is a bit more energy
than most other moleculesthan most other molecules
release becauserelease because all 3all 3
phosphate groups arephosphate groups are
negatively chargednegatively charged and areand are
repelled by each otherrepelled by each other

51. ATP HydrolysisATP Hydrolysis

52. ATPATP
 When ATP donatesWhen ATP donates
a phosphate groupa phosphate group
((phosphorylationphosphorylation) to) to
another molecule,another molecule,
that molecule isthat molecule is
phosphorylated andphosphorylated and
becomesbecomes primedprimed andand
energizedenergized forfor
specific reactionsspecific reactions

53.  Energy is released from storage moleculesEnergy is released from storage molecules
like ATPlike ATP
inin controlledcontrolled
stepssteps via avia a
series ofseries of
intermediateintermediate
moleculesmolecules

54.  Similar to staircases where electronsSimilar to staircases where electrons
flow downflow down the steps from the topthe steps from the top
(most energy) to the bottom(most energy) to the bottom
(least(least
energy),energy),
releasing areleasing a
small amountsmall amount
at each stepat each step
Electron Transport SystemElectron Transport System

55.  Energy isEnergy is
harnessed toharnessed to
move hydrogenmove hydrogen
ionsions
 HH++
ionsions
establishestablish
pHpH
and electricand electric
gradientsgradients
Electron Transport SystemElectron Transport System

56. The ATP ADP CycleThe ATP ADP Cycle
 More ATP isMore ATP is
producedproduced fromfrom
ADP and PADP and Pii byby
using theusing the
energyenergy
releasedreleased fromfrom
exergonicexergonic
reactionsreactions
 This can be done VERYThis can be done VERY
quickly ~10 million moleculesquickly ~10 million molecules
of ATP/second/cellof ATP/second/cell

57. Warm up QuestionsWarm up Questions
1.1. What is phosphorylation?What is phosphorylation?
2.2. How does ATP provide the energy forHow does ATP provide the energy for
endergonic reactions?endergonic reactions?
3.3. Why do the bonds between phosphateWhy do the bonds between phosphate
groups in ATP store so much energy?groups in ATP store so much energy?
4.4. What kind of energy is in chemicalWhat kind of energy is in chemical
bonds?bonds?

58. Objective
Explain, using at least 3
specific details, how
enzymes speed up
chemical reactions

59. Quick ThinkQuick Think
 Which group has more free energy andWhich group has more free energy and
why?why?
 Group 1 = glutamic acid + ammonia + ATPGroup 1 = glutamic acid + ammonia + ATP
 Group 2 = glutamine + ADP + PGroup 2 = glutamine + ADP + Pii

60. EnzymesEnzymes

61. Enzymes help drive metabolic reactionsEnzymes help drive metabolic reactions
 Even if a reaction isEven if a reaction is
spontaneous, it mayspontaneous, it may
happen toohappen too
slowlyslowly to supportto support
the cellthe cell
 Enzymes speed upEnzymes speed up
the process ofthe process of
chemical reactionschemical reactions

62. Living SystemsLiving Systems
 ALL cellularALL cellular
metabolismmetabolism
(reactions)(reactions)
involveinvolve
enzymesenzymes

63.  Begins with a specificBegins with a specific
molecule, which is alteredmolecule, which is altered
through a series of steps,through a series of steps,
and ends with a specificand ends with a specific
productproduct
 How it works:How it works:
Product 1 + (enzyme 1)-->
Product 2 + (enzyme 2)-->
Product 3 + (enzyme 3)-->
Final ProductFinal Product
Enzyme Pathways (aka metabolic pathways)Enzyme Pathways (aka metabolic pathways)

64. Chemical reactions involve both bondChemical reactions involve both bond
breaking and bond formingbreaking and bond forming
 Synthesizing molecules =Synthesizing molecules = anabolic pathwaysanabolic pathways
 Breaking down molecules =Breaking down molecules = catabolic pathwayscatabolic pathways
Complete the sentence:
Endergonic/ExergonicEndergonic/Exergonic reactions occur along
anabolic/catabolicanabolic/catabolic pathways because
_____________________

65. Activation energyActivation energy
 Activation energyActivation energy (aka free energy of(aka free energy of
activation) – the energy required to startactivation) – the energy required to start
a reactiona reaction
 The reactants have to be energized to anThe reactants have to be energized to an
unstable state so that they can breakunstable state so that they can break
their bonds and be primed for new bondstheir bonds and be primed for new bonds
to formto form

66. So activation energy is…So activation energy is…
 The energy needed by molecules inThe energy needed by molecules in
order to reactorder to react

67. Reaction RateReaction Rate
 Initial accelerationInitial acceleration as enzymes & substratesas enzymes & substrates
collidecollide
 Transition stateTransition state
 Collisions atCollisions at
maximum ratemaximum rate
 DecelerationDeceleration
as substratesas substrates
used upused up

68. Inorganic CatalystsInorganic Catalysts
 HeatHeat
 Activation energy is often supplied in the formActivation energy is often supplied in the form
of heat that the reactants absorb from theof heat that the reactants absorb from the
surroundingssurroundings
 LightLight
 PhotosynthesisPhotosynthesis
 ElectricityElectricity
 Decomposition of waterDecomposition of water

69. Activation energyActivation energy
 Heat speeds up reactions – BUTHeat speeds up reactions – BUT
 harms cellsharms cells
 tends to speed up all reactions, not just thetends to speed up all reactions, not just the
ones the cell needsones the cell needs
 Instead, cells use enzymes to catalyzeInstead, cells use enzymes to catalyze
reactionsreactions

70. Increasing Reaction RateIncreasing Reaction Rate
 Enzymes lowerEnzymes lower
the activationthe activation
energyenergy byby
allowing theallowing the
reactants toreactants to
absorb enoughabsorb enough
energy to reachenergy to reach
the transitionthe transition
state at normalstate at normal
temperaturestemperatures

71. http://http://
www.sumanasinc.com/webcontent/animations/contenwww.sumanasinc.com/webcontent/animations/conten
 Animation timeAnimation time

72. OptimumOptimum
ConditionsConditions
 EachEach
enzymeenzyme
has ahas a
specificspecific
range ofrange of
condition incondition in
which itwhich it
works bestworks best

73. Quick ThinkQuick Think
Many spontaneousMany spontaneous
reactions occur veryreactions occur very
slowly. Why donslowly. Why don’t all’t all
spontaneous reactionsspontaneous reactions
occur instantly?occur instantly?

74. Organic CatalystsOrganic Catalysts
 ENZYMESENZYMES
 Have a Specific shapeHave a Specific shape
 Active siteActive site:: crevice where substrate binds tocrevice where substrate binds to
enzyme during a reactionenzyme during a reaction

75. EnzymesEnzymes
 Usually made up of 2 or more subunitsUsually made up of 2 or more subunits
What level ofWhat level of
protein structureprotein structure
is this?is this?
This?This?

76. SubstrateSubstrate
 The reactant an enzyme works on isThe reactant an enzyme works on is
called itcalled it’s substrate – specific to each’s substrate – specific to each
enzymeenzyme
The enzyme-
substrate
complex

77. Lock &Lock &
KeyKey
ActionAction
EnzymesEnzymes
are veryare very
specific andspecific and
can evencan even
distinguishdistinguish
betweenbetween
isomersisomers

78. Induced FitInduced Fit
 Binding of a substrate causes aBinding of a substrate causes a change inchange in
shapeshape, INDUCING an even closer fit with, INDUCING an even closer fit with
substratesubstrate
 This is called the inducedThis is called the induced fitfit
Like a handshake

79. Increasing enzyme actionIncreasing enzyme action
 CooperativityCooperativity –– the binding of onethe binding of one
substrate molecule primes all the othersubstrate molecule primes all the other
subunits of that enzyme for binding tosubunits of that enzyme for binding to
additional substrate moleculesadditional substrate molecules

80. Enzyme activityEnzyme activity
 Substrate bonded to enzyme with weakSubstrate bonded to enzyme with weak
bonds (hydrogen bonds or ionic bonds)bonds (hydrogen bonds or ionic bonds)
 Enzyme catalyzes the reactionEnzyme catalyzes the reaction
 Products are released and enzyme isProducts are released and enzyme is
free to do it againfree to do it again
 Enzymes work very fast ~ 1000Enzymes work very fast ~ 1000
reactions/secondreactions/second

81. Enzyme activityEnzyme activity
 Most reactions are reversibleMost reactions are reversible
 Enzymes can catalyze the reaction inEnzymes can catalyze the reaction in
either directioneither direction
 Always work in the direction towardAlways work in the direction toward
equilibriumequilibrium

82. Enzyme activityEnzyme activity
 Enzymes help by:Enzymes help by:
 Orienting theOrienting the
reactants properlyreactants properly
so they can reactso they can react
 Stretching andStretching and
bending reactantsbending reactants
to help them get toto help them get to
the transition statethe transition state
fasterfaster
 Provides aProvides a
microenvironmentmicroenvironment
more suitable formore suitable for
the reaction tothe reaction to
occuroccur

83. http://http://
www.sumanasinc.com/webcontent/animations/contenwww.sumanasinc.com/webcontent/animations/conten
 Animation timeAnimation time

84. Quick ThinkQuick Think
Describe why enzymesDescribe why enzymes
only react on specificonly react on specific
substratessubstrates

85. Enzyme activityEnzyme activity
may be inhibitedmay be inhibited
by a variety ofby a variety of
factorsfactors

86. Inorganic InhibitorsInorganic Inhibitors
 HEATHEAT
 Breaks bonds, causes enzymes toBreaks bonds, causes enzymes to
lose their tertiary shapelose their tertiary shape
 Some enzymes will "snap back" onSome enzymes will "snap back" on
coolingcooling
 Some never regain their structureSome never regain their structure

87. Inorganic InhibitorsInorganic Inhibitors
 pHpH
 Change in pHChange in pH
alters thealters the
tertiarytertiary
structure ofstructure of
the enzymethe enzyme

88.  Competitive InhibitorsCompetitive Inhibitors
 Blocks the active siteBlocks the active site
 Substrate cannot bond toSubstrate cannot bond to
enzymeenzyme
Inhibiting Enzyme ActionInhibiting Enzyme Action

89.  Allosteric INHIBITORAllosteric INHIBITOR
MoleculesMolecules
 aka non-competitive inhibitorsaka non-competitive inhibitors
 attaches to a site that isattaches to a site that is
not the active sitenot the active site
 Changes the shape of theChanges the shape of the
enzymeenzyme

90.  IRREVERSIBLE INHIBITIONIRREVERSIBLE INHIBITION
 Substances that permanently change the tertiarySubstances that permanently change the tertiary
shape of an enzyme,shape of an enzyme, DENATURING ITDENATURING IT
 Usually due to covalent bonding with the enzymeUsually due to covalent bonding with the enzyme
 Many toxins and poisons do thisMany toxins and poisons do this
 Nerve gases, penicillinNerve gases, penicillin
Inhibiting Enzyme ActionInhibiting Enzyme Action

91. Feedback InhibitionFeedback Inhibition
Pathway has a product which blocks the actionPathway has a product which blocks the action
of enzymes early in the pathwayof enzymes early in the pathway (turns itself(turns itself
off!)off!)

92. Inhibiting Enzyme ActionInhibiting Enzyme Action
 Not always a bad thingNot always a bad thing
 It is one way the cell controls chemicalIt is one way the cell controls chemical
reactionsreactions

93. Quick ThinkQuick Think
 What are some ways thatWhat are some ways that
enzyme activity can beenzyme activity can be
inhibited?inhibited?
 Why is this good for livingWhy is this good for living
systems?systems?

94. Enzyme activityEnzyme activity
must be regulatedmust be regulated
by the cellby the cell

95. Enzyme activityEnzyme activity
 Some enzymes requireSome enzymes require
cofactorscofactors
 NonproteinNonprotein
 Organic or inorganicOrganic or inorganic
 If organic called aIf organic called a
coenzymecoenzyme
 Permanently attached orPermanently attached or
loosely attachedloosely attached
 Help enzyme functionHelp enzyme function

96.  Allosteric regulationAllosteric regulation
 Allosteric moleculesAllosteric molecules must bemust be
present for some enzymes to workpresent for some enzymes to work
properlyproperly
 Often ions orOften ions or
vitaminsvitamins
Regulating Enzyme ActionRegulating Enzyme Action
AllostericAllosteric
moleculemolecule
binds tobinds to
enzyme andenzyme and
changes it to achanges it to a
functionalfunctional
shapeshape

97. Increasing Enzyme ActionIncreasing Enzyme Action
 Allosteric ACTIVATOR moleculesAllosteric ACTIVATOR molecules
 Holds substrate in place or causes aHolds substrate in place or causes a
shape change in the enzyme so itshape change in the enzyme so it “fits”“fits”
substrates bettersubstrates better

98. EnzymeEnzyme
PathwaysPathways

99. Enzyme PathwaysEnzyme Pathways
 AdvantagesAdvantages
 Similar enzymes canSimilar enzymes can
bebe segregatedsegregated within awithin a
cellcell
 Little accumulationLittle accumulation ofof
intermediate productsintermediate products
 Removes product ofRemoves product of
each reaction from theeach reaction from the
system so thatsystem so that
CHEMICALCHEMICAL
EQUILIBRIUMEQUILIBRIUM isis nevernever
reachedreached
mitochondrion