Term
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Definition
All of the biochemical reactions occurring within a living organism.
Catabolism: Breakdown of nutrience to generate energy and raw materials.
Anabolism: Use of energy and raw materials to produce cellular molecules. |
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Definition
| The ability of a cell to extract stored potential energy from molecules and convert it into kinetic energy to perform tasks. |
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Term
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Definition
First Law (conservation of energy): Energy may neither be created or destroyed, it can only change form.
Second Law: All systems tend towards entropy. Only a portion of potential energy can be converted into kinetic energy. This portion is called "free energy (G)". |
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Term
| Change in Free Energy (ΔG) |
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Definition
The amount of energy in the reactants is alwas different than the amount of energy in the products.
Gsubstrates - Gproducts = ΔG |
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Term
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Definition
| The substrates (reactants) contain more energy than the products. Reaction has a -ΔG value. |
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Definition
| The substrates (reactants) contain less energy than the products. Reaction has a +ΔG value. |
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Term
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Definition
| Endergonic reactions require energy, this energy must come from an exergonic reaction. Therefore, the two reactions are "coupled". |
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Term
| ATP (adenosine tri-phosphate) |
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Definition
| The energy currency of the cell. Usually tranfers a phosphate to a substrate molecule to start a reaction (becoming ADP). Sometime ATP releases two phosphates (ppi or pyrophosphate) to become AMP. |
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Term
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Definition
| Amount of energy initially needed to break the bonds in the substrate (in exergonic reactions). Amount of energy needed is the "energy of activation (EA)". Addition of this energy converts the substrate into a "transition state". The greater the EA,the slower the rate of the reaction. |
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| Methods for Increasing the Rate of a Reaction |
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Definition
Increasing temperature: Reaction rate doubles with every 10ºC increase.
Using a catalyst. |
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Term
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Definition
| Biological catalysts. Take reactions through an alternate transition state that has a much lower activation energy. Enzymes contain "active sites" to which substrates bind (as long as the substrates fit into the shape of the active site). |
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Term
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Definition
| RNA catalysts that are not enzymes. |
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Term
| Mechanism of Enzyme Action |
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Definition
| Enzyme orientates the substrates into the correct positions. Enzyme creates a "micro-environment" that turns the substrates into intermediates. The enzyme puts stress on the products that bends the bonds and creates a final shape. |
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Term
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Definition
| Inorganic metal ions that are permanently attached to an enzyme and aid in that enzymes functions. |
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Term
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Definition
| Organic molecules that temporarily combine with an enzyme to aid it in a reaction. Three common coenzymes: NADH (nicotinamide adenine dinucleotide), NADPH (nicotinamide adenine dinucleotide phosphate), and FADH2 (flavin adenine dinucleotide). Coenzymes can exist in both oxidized and reduced forms and function as carriers of electrons/protons between oxidation and reduction reactions. |
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Term
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Definition
| Paired oxidation and reduction reactions. |
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Term
| Conditions for Enzyme Function |
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Definition
| There are maximum, minimum, and optimal conditions in which an enzyme will function. For pH, the optimal condition is in between the max. and min. on a bell-shaped curve. For temperature, the optimum is very close to the maximum. |
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Term
| Reaction Organization in Metabolism |
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Definition
| Reactions are organized into pathways in which each separate reaction is mediated by an enzyme. Usually the buildup of an intermediate product will activate the next reaction in the series, and the buildup of the end product will inhibit the first reaction in the series (negative feedback). |
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| Mechanisms of Enzyme Inhibition |
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Definition
1. Competitive inhibition: The inhibitor binds to the same site that the substrates do (% of inhibition is determined by the relitive concentrations of the inhibitor and the substrate).
2. Noncompetitive inhibition: The inhibitor binds to a seperate site (the concentration of the substrate does not matter). |
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Term
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Definition
| Alosteric enzymes contain multiple subunits and exist in either an active or an inactive form (all active or none active). An "activator" molecule activates the enzyme and an "inhibitor" molecule inhibits the enzyme. |
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Term
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Definition
| When subunits act independently of each other. In hemoglobin, the activation of one subunit activates the next one ect... Is different than allosteric regulation. |
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