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| 55496640 | metabolism | the total of an organism's chemical reactions; an emergent property of life that arises from interactions between molecules within the orderly environment of the cell | |
| 55496641 | metabolic pathway | begins with a specific molecule, which is then altered in a series of defined steps, resulting in a specific product; each step of the pathway is catalyzed by a specific enzyme | |
| 55496642 | catabolic pathway | a metabolic process that breaks down complex molecules into simpler compounds; example = cellular respiration because it breaks glucose into carbon dioxide and water; the energy that is stored becomes available to do work within the cell | |
| 55496643 | anabolic pathway | a metabolic process that consumes energy to build complicated molecules from simpler molecules | |
| 55496644 | bioenergetics | the study of how energy flows through living organisms | |
| 55496645 | energy | the capacity to cause change | |
| 55496646 | kinetic energy | the relative motion of an object | |
| 55496647 | heat energy | kinetic energy associated with random movement of atoms or molecules | |
| 55496648 | potential energy | the energy that matter possesses because of its location or structure when it is at rest; due to arrangement of atoms | |
| 55496649 | chemical energy | the type of energy that refers to the potential energy available for release in a chemical reaction; glucose, for example, has a high amount of this | |
| 55496650 | thermodynamics | the study of energy transformations that occur in a collection of matter | |
| 55496651 | first law of thermodynamics | a rule that states that the energy of the universe is constant; energy can be transferred and transformed, but it cannot be created or destroyed | |
| 55496652 | entropy | disorder of the universe | |
| 55496653 | second law of thermodynamics | a rule that states that every energy transfer or transformation increases the entropy (disorder) of the universe; unstoppable trend toward randomization of the universe as a whole | |
| 55496654 | free energy | the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell; this type of energy is a measure of a system's instability, meaning its tendency to change to a more stable state | |
| 55496655 | exergonic | the type of reaction that proceeds with a net release of free energy; because the chemical mixture loses free energy, Gibbs free energy is negative; it is a spontaneous reaction | |
| 55496656 | endergonic | the type of reaction that absorbs free energy from surroundings; because energy is stored in molecules, Gibbs free energy is positive; the reaction is nonspontaneous | |
| 55496657 | energy coupling | the use of an exergonic process to drive an endergonic one; ATP is responsible for mediating this, and it acts as an energy source | |
| 55496658 | ATP | this molecule is composed of ribose, adenine, and a chain of three phosphate groups | |
| 55496659 | phosphorylated | the state of a molecule when it receives a phosphate, such as in ATP hydrolysis, making it more reactive (less stable) than the original molecule | |
| 55496660 | enzyme | a macromolecule that acts as a catalyst; without this, pathways of metabolism would be congested because reactions would take so long | |
| 55496661 | catalyst | a chemical agent that speeds up a reaction without being consumed by the reaction; enzymes are examples of these | |
| 55496662 | activation energy | the initial investment of energy for starting a reaction; the energy required to destabilize the reactant molecules so their bonds can break; also, the amount of energy needed to push reactants over a "hill" so that the "downhill" part of the reaction can begin | |
| 55496663 | enzyme-substrate complex | the entity that forms when an enzyme bonds to a substrate, in which the enzyme's catalytic reaction converts the substrate to the product of the reaction | |
| 55496664 | active site | a pocket or groove on the surface of an enzyme where catalysis occurs; there is only one of these per enzyme; this is formed by a few amino acids while others construct a frame for it | |
| 55496665 | induced fit | the model for enzymes that says that as the substrate and active site approach each other, each influences the other's shape so they mold together; compared to a proper handshake: both entities conform to make a good grip in order to interact | |
| 55496666 | cofactors | nonprotein helpers for catalytic reactions; these may be bound tightly to an enzyme as a permanent resident, or may be bound loosely and reversibly along the substrate | |
| 55496667 | coenzyme | cofactors that are inorganic; examples of these are vitamins | |
| 55496668 | competitive inhibitors | reversible inhibitors that resemble the normal substrate molecule and compete for admission into the active site; these reduce productivity by blocking substrates from entering active sites; these can be overcome by producing more substrates to outnumber them; poisons are an example of these with strong bonds | |
| 55496669 | noncompetitive inhibitors | these molecules do not directly compete with substrates--instead, they bind to another part of the enzyme, causing it to change its shape so that the active site becomes less effective at conversion | |
| 55496670 | allosteric regulation | this occurs when a molecule bonds to some other location on an enzyme, causing a conformational change, which blocks the active site; after the molecule leaves, however, the enzyme returns to its original shape; may result in either inhibition or enhanced activity of an enzyme | |
| 55496671 | cooperativity | a mechanism that amplifies the response of an enzyme to a substrate by leading one substrate molecule to prime an enzyme's acceptance of additional substrate molecules | |
| 55496672 | feedback inhibition | an occurrence in which a metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway; this prevents the cell from wasting chemical resources; when an end product stops or slows its own production |
