Chapter 8: An Introduction to Metabolism Vocabulary Flashcards

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