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22 Cards in this Set
- Front
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Define metabolic pathway |
A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule into simpler compounds (catabolic pathway). A metabolic pathway begins with a specific molecule and ends with a product. Each step is catalyzed by a specific enzyme |
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Differentiate between catabolic and anabolic pathways |
Anabolic pathway: metabolic pathway that consume energy to synthesize a complex molecule from simpler compounds Catabolic pathway: in a cell releases free energy in a series of reactions |
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Differentiate between spontaneous and non-spontaneous processes |
Spontaneous processes: occur without energy input; they can happen quickly or slowly Nonspontaneous reactions require an input of energy to take place. |
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An exergonic reaction proceeds with a net release of free energy and is spontaneous |
Release of free energy and is spontaneous |
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An endergonic reaction absorbs free energy from its surroundings and is nonspontaneous |
Absorbs free energy from its surroundings and is nonspontaneous |
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Define the different forms of energy, with examples |
Kinetic energy is energy associated with motionHeat (thermal energy) is kinetic energy associated with random movement of atomsor molecules Potential energy is energy that matter possesses because of its location or structure Chemical energy is potential energy availablefor release in a chemical reaction |
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Define a cell/system in equilibrium in terms of free energy. |
Free energy is a measure of a system’s instability, its tendency to change to a more stable state. During a spontaneous change, free energy decreases and the stability of a system increasesEquilibrium is a state of maximum stability. A process is spontaneous and can perform work only when it is moving toward equilibrium |
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Exergonic and endergonic reactions are and what happens to the value of G during the course of these reactions. |
NEGATIVE Delta G for spontaneous reactions. POSITIVE Delta G for non-spontaneous |
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Thermodynamics |
is the study of energy transformations |
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First law of thermodynamics |
Energy can be transferred and transformed,but it cannot be created or destroyedThe first law is also called the principle of conservation of energy |
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Second law of thermodynamics |
Every energy transfer or transformation increases the entropy (disorder) of the universe Ordered forms of energy are at least partly converted to heat. |
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Free Energy |
The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system. (The change in free energy of a system is calculated by the equation ΔG = ΔH – TΔS, where H is enthalpy [in biological systems, equivalent to total energy], T is absolute temperature, and S is entropy.) |
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Define entropy and know how it increases with every energy transformation. |
Entropy: a measure of disorder, or randomness |
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Energy coupling. Give an example |
In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction Most energy coupling in cells is mediated by ATP Ex: ATP which can become ADP+energy |
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Role of enzymes in chemical reactions and how they lower the activation energy. |
Enzymes are proteins that regulate chemical reactions but are themselves unchanged by the reaction. Because they’re often required to start or speed up a reaction, enzymes also are called catalysts. Without enzymes, many biochemical reactions would be energetically inefficient. |
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How enzymes lower the activation energy. |
Enzymes lower the activation energy of a reaction by binding one of the reactants, called a substrate, and holding it in a way that lowers the activation energy. |
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Active site |
The specific portion of an enzyme that binds the substrate(the reactant on which an enzyme works) by means of multiple weak interactions and that forms the pocket in which catalysis occurs |
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competitive inhibitor |
A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics |
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noncompetitive inhibitor |
A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer functions effectively. |
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cofactors |
Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely with the substrate during catalysis. |
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coenzyme |
An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions. |
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