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38 Cards in this Set
- Front
- Back
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free energy -what -based on |
-nrg of reactants and products and if the reaction will happen spontaneously or not -chemical nrg and concentration |
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reactants want to go from ______ nrg to ______ nrg |
high to low |
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equilibrium means free nrg... |
of reactants and products is equal |
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change in G |
free energy tells us if a rxn will happen, but not how fast |
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what are enzymes for? |
to speed up chemical reactions |
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Activation energy (Ea) |
the amount of energy the colliding particles must have for reactants to get over the barrier and become products |
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size of activation energy determines what? |
reaction rate (how fast a reaction occurs) |
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higher activation energy = |
slower the reaction lower number of reactants turning into proucts ("productive collisions") |
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lower activation energy = |
faster reaction greater the number of reactants turning to products ("productive collisions") |
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catalyst |
a substance that accelerates a chemical rxn |
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what happens to the activation energy of a catalyzed reaction? |
lower activation nrg |
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Can a catalyst change the free energies of the unbound reactants or products or the equilibrium? |
no |
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equilibrium constant K |
multiplied product concentration DIVIDED by multiplied reactant concentration |
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K is smaller than .001 |
basically no reaction occurs |
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K is .001- 1 |
at equilibrium; more reactants than products |
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K is 1- 1000 |
at equilibrium; more products than reactants |
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K at 1 |
products and reactants are equal |
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K larger than 1000 |
basically reaction goes to completion |
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Le Chatelier's Principle ex: |
when stress is applied to a system of equilibrium,equilibrium shifts to relieve stress Stress? change in concentration, pressure, temperature, volume, that disturb original equilibrium ex: buffers! |
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Catalysts can change the _____, but not the ______of a reaction. |
rate equilibrium |
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what determines equilibria? |
free energies of the UNBOUND reactants and products |
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enzyme |
a protein or other molecule that catalyzes a biological rxn |
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active site |
specific pocket within the enzyme with a specific shape and chemical makeup needed to bind to a substrate where substrate binds on the enzyme |
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most enzymes are ____? |
proteins |
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how do RNA molecules act as catalysts? |
ribosomes |
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substrate |
the reactant in an enzyme catalyzed |
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what makes sucrose taste sweet? |
sweet taste receptor accepts (not specific) and sends signal to the brain |
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how does sucrose have calories? |
binds to protein sucrase (very specific) that begins sucrase metabolism |
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specificity (of enzyme) |
enzyme's limitation of activity to specific substrate or type of reaction |
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enzyme papain |
can break down peptide bonds in MANY different proteins, not just papaya fruit (where the enzyme is from) |
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enzyme thrombin |
catalyzes hydrolysis of peptide bond adjacent to arginine in a protein essential for blood clotting |
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enzyme catalase |
for the decompostion of hydrogen peroxide which can damage DNA |
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turnover # *most enzymes? |
measures catalytic activity max # of substrate molecules acted upon per enzyme per unit of time *most enzymes turn over= 10-1000 molecules per second |
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-enzyme with very fast turnover rate? |
-catalase (hydrogen peroxide to water and O2)10^7 -papain (hydrolysis of peptide bonds) 10 |
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cofactor *usually what? (2) |
a nonprotein part of an enzyme that is essential to the enzyme's catalytic activity *usually metal ion or coenzyme *trace minerals and vitamins |
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coenzyme ex: |
an organic molecule that acts as an enzyme cofactor ***electron carriers ex: NADH, FADH, NADPH |
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why are cofactors needed? |
proteins are limited to the 20 amino acid side chains and to do all the things they want to.....need more things |
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6 Enzyme Classifications |
1. oxidoreductases 2. transferases 3. hydrolases 4. ligases 5. isomerases 6. lyases |
