MetabolismMetabolism
Cell EnergeticsCell Energetics
Cell do three Cell do three mainmain kinds of work kinds of work Mechanical – move themselvesMechanical – move themselves Transport – move something elseTransport – move something else Chemical – convert stuff to other stuffChemical – convert stuff to other stuff
Work requires energyWork requires energy Where does the energy come from and Where does the energy come from and
how do cells use it?how do cells use it?
Cell EnergeticsCell Energetics
Energy is ______Energy is ______ Metabolism Metabolism 2 types of metabolism2 types of metabolism Two forms of energyTwo forms of energy
How do cells use the 2 formsHow do cells use the 2 forms 2 Laws of Thermodynamics2 Laws of Thermodynamics Entropy Entropy 2 types of reactions 2 types of reactions
Cell EnergeticsCell Energetics
MetabolismMetabolism = total of all the = total of all the chemical reactions taking place in chemical reactions taking place in
an organisman organism
MetabolismMetabolism
AnabolismAnabolism = ‘= ‘build up’ processes; build up’ processes; ‘consume’ (store) energy by ‘consume’ (store) energy by assembling macromolecules assembling macromolecules PhotosynthesisPhotosynthesis
CatabolismCatabolism = ‘break down’ = ‘break down’ reactions; release energy by reactions; release energy by breaking down (lyse) molecules breaking down (lyse) molecules DigestionDigestion
EnergyEnergy
Energy – the ability to do workEnergy – the ability to do work PotentialPotential = capacity to do = capacity to do
work (move something); due work (move something); due to to positionposition or stored (chemical or stored (chemical energy; glucose, glycogen)energy; glucose, glycogen)
KineticKinetic = motion = motion EquilibriumEquilibrium = energy runs out = energy runs out
Kinetic and potential energyKinetic and potential energy
What does the types of energy have to do with biology?
Thermodynamics Thermodynamics
11stst Law – energy cannot be created nor Law – energy cannot be created nor destroyeddestroyed Energy Energy cancan be transformed be transformed
22ndnd Law – ‘Law of Law – ‘Law of EntropyEntropy’ whenever energy is ’ whenever energy is transformed, some of it becomes ‘unusable’transformed, some of it becomes ‘unusable’
Entropy - Entropy - amount of usable energy decreases amount of usable energy decreases each time it is usedeach time it is used ‘‘Lost’ as heatLost’ as heat Energy is running down, universe is tending Energy is running down, universe is tending
towards disordertowards disorder
Biological Order and DisorderBiological Order and Disorder
Organisms are Organisms are openopen systems systems Use energy to maintain order and Use energy to maintain order and
organization organization Trade organization for heat (increase Trade organization for heat (increase
entropy in the environment)entropy in the environment)
Metabolism: ReactionsMetabolism: Reactions Two types of reactions:Two types of reactions:
Exergonic, endergonic Exergonic, endergonic Exergonic reactionExergonic reaction - - release of free release of free
energyenergy Less stable, more workLess stable, more work Fire, respiration Fire, respiration
Metabolism: ReactionsMetabolism: Reactions
Endergonic reactionEndergonic reaction - - energy is energy is absorbed/storedabsorbed/stored Photosynthesis Photosynthesis
Chemical ReactionsChemical Reactions
Equilibrium is Equilibrium is eventually eventually reached in closed reached in closed systemssystems Reduced free Reduced free
energyenergy No work is doneNo work is done You’re dead!You’re dead!
What cells do..
ReviewReview
What are the 2 forms of energy?What are the 2 forms of energy? _____ is the ability to do work_____ is the ability to do work Energy is lost in chemical reactions as __Energy is lost in chemical reactions as __ A reaction that stores/absorbs energy is A reaction that stores/absorbs energy is
said to be _____said to be _____ A reaction that releases energy is _____A reaction that releases energy is _____ The total of all chemical reactions in an The total of all chemical reactions in an
organism is called ____organism is called ____
Coupled ReactionsCoupled Reactions Living systems use coupled Living systems use coupled
reactions reactions Endergonic reactions are linked Endergonic reactions are linked
((coupledcoupled) with exergonic reactions) with exergonic reactions Energy from an exergonic reaction Energy from an exergonic reaction
(respiration) is stored in chemical (respiration) is stored in chemical bondsbonds
Coupled ReactionsCoupled Reactions
ATP – Adenosine triphosphateATP – Adenosine triphosphate Cyclical Cyclical Catabolic pathways drive the Catabolic pathways drive the
regeneration of ATP from ADP and regeneration of ATP from ADP and phosphatephosphate
Controlled by Controlled by enzymesenzymes
Uses of EnergyUses of Energy
Mechanical -Mechanical - moving of moving of cilia/flagella, muscle, cilia/flagella, muscle, cytoplasm, chromosomes cytoplasm, chromosomes (mitosis), mousetrap(mitosis), mousetrap
Transport -Transport - H+ ‘pump’, receptors H+ ‘pump’, receptors Chemical –Chemical – polymerization polymerization
BioluminescenceBioluminescence
• EnzymesEnzymes controlcontrol metabolism – metabolism – If enzymes are present, If enzymes are present, reactions take place, if not, reactions take place, if not, they don’t.they don’t.Enzymes speed up reactions by Enzymes speed up reactions by lowering activation energylowering activation energy
Biological catalystsBiological catalysts Accelerate a reaction without being Accelerate a reaction without being
changed changed Proteins (700)Proteins (700)
Catabolic or anabolic reactionsCatabolic or anabolic reactions
EnzymesEnzymes
Enzymes Enzymes All chemical reactions require All chemical reactions require
activation energyactivation energy Activation energy (EActivation energy (EAA)) - the - the
initial amount of energy needed initial amount of energy needed to start a chemical reaction to start a chemical reaction
Transition stateTransition state = reactants have absorbed = reactants have absorbed energyenergy Have become unstableHave become unstable Reaction takes placeReaction takes place
EnzymeEnzymess Some reactions occur Some reactions occur
spontaneously due to spontaneously due to heat from the heat from the environment (rust)environment (rust)
Cellular T needs to Cellular T needs to remain lowremain low
Metabolism is too slow at Metabolism is too slow at low Tlow T Starch to glucoseStarch to glucose
EnzymesEnzymes used to used to reducereduce activation energy activation energy (metabolism at lower T)(metabolism at lower T)
EnzymesEnzymes SubstrateSubstrate = substance enzyme acts on = substance enzyme acts on Active siteActive site = area on the enzyme where = area on the enzyme where
substrate binds substrate binds Verryyy specificVerryyy specific Groove, pocket = 3d shapeGroove, pocket = 3d shape
EnzymesEnzymes Lock and key mechanismLock and key mechanism Induced FitInduced Fit = enzyme may change shape = enzyme may change shape
to allow better reaction on substrateto allow better reaction on substrate
Factors That Affect Enzyme Factors That Affect Enzyme Activity Activity
TemperatureTemperature pHpH Inorganic salts – Inorganic salts –
Disrupt H bonds, ionic bonds, Disrupt H bonds, ionic bonds, hydrophobic interactionshydrophobic interactions
CofactorsCofactors InhibitorsInhibitors
Temperature and pH affect
enzyme activity
CofactorsCofactors
Cofactors - nonprotein enzyme Cofactors - nonprotein enzyme helpershelpers Metals – Fe, Zn, CuMetals – Fe, Zn, Cu
Coenzymes - organic cofactorsCoenzymes - organic cofactors Vitamins Vitamins
InhibitorsInhibitors = substances that inhibit = substances that inhibit the actions of enzymes (2 kinds:)the actions of enzymes (2 kinds:) Competitive inhibitorsCompetitive inhibitors Noncompetitive inhibitorsNoncompetitive inhibitors
EnzymesEnzymes
Competitive inhibitors - resemble substrate, block active site Neurotoxin, Disulfiram
Noncompetitive Noncompetitive inhibitors - inhibitors - causes causes enzyme to change enzyme to change shapeshape Destroys Destroys
conformation (active conformation (active site)site)
DDT, nerve gas (DSF)DDT, nerve gas (DSF) May be May be allosteric allosteric
regulationregulation
EnzymesEnzymes
Allosteric Regulation of Allosteric Regulation of EnzymesEnzymes
AllostericAllosteric regulation - a protein’s regulation - a protein’s function at one site is affected function at one site is affected by binding of a regulatory by binding of a regulatory molecule at another sitemolecule at another site
Receptor siteReceptor site located away from located away from the active site (quatenary the active site (quatenary structure)structure)
Allosteric site has to be Allosteric site has to be activated, (may be inhibited)activated, (may be inhibited)
Allosteric activator
Allosteric inhibitor
Cooperativity -Cooperativity - oneone substrate molecule substrate molecule can activate all other can activate all other subunits of an enzymesubunits of an enzyme Induced fitInduced fit
Only requires a small Only requires a small concentration of concentration of substrate to activate substrate to activate enzymeenzyme
EnzymesEnzymes
Enzyme Activity Helps Control Enzyme Activity Helps Control MetabolismMetabolism
A cell’s metabolic pathways must be A cell’s metabolic pathways must be tightly regulatedtightly regulated
DNA codes for proteins (enzymes)DNA codes for proteins (enzymes) Amount of enzyme can determine Amount of enzyme can determine
rate of reactionrate of reaction Feedback Inhibition - Feedback Inhibition - end product of end product of
the pathway inhibits the pathwaythe pathway inhibits the pathway
Regulation Regulation
Metabolic pathways – series of enzymes Metabolic pathways – series of enzymes creates small steps to a final productcreates small steps to a final product
Controlling the enzymes (activity or Controlling the enzymes (activity or production) controls the pathway and production) controls the pathway and product(s)product(s)
Feedback InhibitionFeedback Inhibition
Final product of the Final product of the pathway shuts off the pathway shuts off the pathwaypathway
Feedback inhibition Feedback inhibition prevents cells from prevents cells from wasting resourceswasting resources ““don’t need gas if you don’t need gas if you
don’t have a car.”don’t have a car.”
Isoleucine – allosteric inhibitor