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CH6 Energy and Metabolism
n/a
22
Biology
Undergraduate 1
10/11/2010

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Term
Energy
Definition
capacity to do work, kinetic and potential
Term
First law of thermodynamics
Definition
Energy cannot be created or destroyed, Can only change from one form to another
Term
Second law of thermodynamics
Definition
Entropy (disorder) is continuously increasing, Energy transformations proceed spontaneously to convert matter from a more ordered/ less stable form to a less ordered/ more stable form
Term
G = H – TS
Definition
G = Energy available to do work
H = enthalpy, energy in a molecule’s chemical bonds
T = absolute temperature
S = entropy, unavailable energy
Term
Positive ΔG
Definition
Products have more free energy than reactants;Endergonic – end up with “stored energy”
Not spontaneous (requires input of energy
Term
Neagtive ΔG
Definition
Products have less free energy than reactants; Exergonic – there is a “release” of energy
Spontaneous (may not be instant)
Term
Catalysts
Definition
Substances that influence chemical bonds in a way that lowers activation energy
Term
ATP =
Definition
Ribose – 5 carbon sugar, Adenine, Chain of 3 phosphates; Key to energy storage, Bonds are unstable
Term
Enzymes
Definition
Most are protein, shape stabilizes a temporary association between substrates, not changed or consumed in reaction, Catalyzes a reaction
Term
Active site
Definition
Pockets or clefts for substrate binding, Applies stress to distort particular bond to lower activation energy (Induced fit)
Term
Nonprotein enzymes
Definition
i.e. Ribozymes; Intramolecular catalysis – catalyze reaction on RNA molecule itself
Intermolecular catalysis – RNA acts on another molecule
Term
Inhibitor
Definition
substance that binds to enzyme and decreases its activity
Term
Competitive inhibitor
Definition
Competes with substrate for active site
Methanol (formaldehyde&blindness) vs Ethanol
Term
Noncompetitive inhibitor
Definition
Binds to enzyme at a site other than active site
Causes shape change that makes enzyme unable to bind substrate
Term
Allosteric enzymes
Definition
enzymes exist in active and inactive forms
Term
Most noncompetitive inhibitors...
Definition
bind to allosteric site – chemical “on/off” switch
Term
Allosteric inhibitor
Definition
binds to allosteric site and reduces enzyme activity
Term
Allosteric activator
Definition
binds to allosteric site and increases enzyme activity
Term
Metabolism
Definition
Total of all chemical reactions carried out by an organism
Term
Anabolic reactions / anabolism
Definition
Expend energy to build up molecules (more subject to feedback inhibition)
Term
Catabolic reactions/ catabolism
Definition
Harvest energy by breaking down molecules (feedback = heat)
Term
Feedback inhibition
Definition
End-product of pathway binds to an allosteric site on enzyme that catalyses first reaction in pathway;
Shuts down pathway so raw materials and energy are not wasted
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