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flinkexistenceMechanics

Oct 27, 2013 (4 years and 12 days ago)

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Ground Rules of Metabolism


Energy = capacity to do work


Potential Energy

stored energy in resting
object


Kinetic Energy

energy of motion



1
st

Law of Thermodynamics: Energy cannot
be created or destroyed


Converted from one form to another


2
nd

Law of Thermodynamics: Energy flows
from organized to disorganized forms


Concentrated energy tends to disperse
spontaneously


Moves from useable to non
-
useable energy


Chemical bonds resist this direction of energy
flow



Entropy: Measure of randomness or disorder
in a system


Organized energy = useable = less entropy


Disorganized = not useable = more entropy



Living things must maintain ongoing
replacement of lost energy



All chemical reactions within a cell or
organism


Reactants


Products






+


=


Anabolic


Building reactions (dehydration synthesis)


Endergonic

need energy


A + B + Energy = C


Usually not spontaneous


Catabolic


Breaking down reactions (hydrolysis)


Exergonic

release energy


C = A + B + Energy


Usually spontaneous


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.


Endergonic

coupled with
exergonic


Released energy from one fuels other


C = A +B + Energy









D + E + Energy = F


Energy source for cells


Created by photosynthesis or in mitochondria


Breaking down ATP releases energy


This powers cell
fuctions


E.g. Active transport proteins


Biological catalysts


Speed up chemical reactions


Don’t start reactions on their own


Reusable


Can catalyze in forward & reverse


Very specific!


Substrate attaches to enzyme’s active site



Lowers activation energy


Makes reactions faster & easier


Concentration


Enzymes


Reactants


Products


Temperature


pH


Enzyme cofactors


vitamins


Inhibition


Competitive

binds to site first or more strongly


Non
-
competitive

binds to different area,
changing enzyme bonding area


Feedback inhibition


Product of reaction binds to
allosteric

site


Shuts down reaction