ground rules of metabolism energy = capacity to do work potential energy—stored energy in...
TRANSCRIPT
CHAPTER 6Ground Rules of Metabolism
ENERGY Energy = capacity to do work Potential Energy—stored energy in
resting object Kinetic Energy—energy of motion
THERMODYNAMICS 1st Law of Thermodynamics: Energy
cannot be created or destroyedConverted from one form to another
2nd Law of Thermodynamics: Energy flows from organized to disorganized formsConcentrated energy tends to disperse
spontaneouslyMoves from useable to non-useable energyChemical bonds resist this direction of
energy flow
THERMODYNAMICS Entropy: Measure of randomness or
disorder in a systemOrganized energy = useable = less entropyDisorganized = not useable = more entropy
Living things must maintain ongoing replacement of lost energy
METABOLISM All chemical reactions within a cell or
organism Reactants Products
+ =
CHEMICAL REACTIONS Anabolic
Building reactions (dehydration synthesis)Endergonic—need energyA + B + Energy = CUsually not spontaneous
CatabolicBreaking down reactions (hydrolysis)Exergonic—release energyC = A + B + EnergyUsually spontaneous
CHEMICAL REACTIONS Activation Energy—minimum energy
that can get a reaction to run on it’s own.Cells control energy input into reactions,
therefore controlling timing & speed of reactions.
CHEMICAL REACTIONS Endergonic coupled with exergonic Released energy from one fuels other
C = A +B + Energy
D + E + Energy = F
ATP Energy source for cells Created by photosynthesis or in
mitochondria
ATP
ATP Breaking down ATP releases energy This powers cell fuctions
E.g. Active transport proteins
ENZYMES Biological catalysts
Speed up chemical reactionsDon’t start reactions on their own
Reusable Can catalyze in forward & reverse Very specific!
Substrate attaches to enzyme’s active site
ENZYMES Lowers activation energy
Makes reactions faster & easier
CONTROLS OVER ENZYMES Concentration
EnzymesReactantsProducts
Temperature pH Enzyme cofactors
vitamins
CONTROLS OVER ENZYMES Inhibition
Competitive—binds to site first or more strongly
Non-competitive—binds to different area, changing enzyme bonding area
CONTROLS OVER ENZYMES Feedback inhibition
Product of reaction binds to allosteric siteShuts down reaction