AP BIO-CH 6 Vocab

Metabolism: Energy and Enzymes
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substrate or reactant (ligand)
reactant ins a reaction controlled by an enzyme
activation energy
energy that must be added in order for molecules to react with one another
free energy
useful energy in a system that is capable of performing work
endergonic reaction
chemical reaction that requires an input of energy; the opposite of an exergonic rn
exergonic reaction
chemical reaction that releases energy; opposite of endergonic rn
enzyme
organic catalyst, usually a protein, that speeds a reaction in cells due to its particular shape
catalysts
(chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected
competitive inhibitor
form of enzyme inhibition where the substrate and inhibitor are both able to bind to the enzyme's active site. Only when the substrate is at the active site will product form
noncompetitive inhibitor
form of enzyme inhibition where the inhibitor binds to an enzyme at a location other than the active site; while at this site, the enzyme shape changes, the inhibitor is unable to bind to its substrate, and no product forms
active site
region of the surface of an enzyme where the substrate binds and where the reaction occurs
product
substance that forms as the result of a reaction
allosteric regulation
In biochemistry, 'allosteric regulation' is the regulation of an enzyme or protein by binding an effector molecule at the protein's allosteric site (that is, a site other than the protein's active site). Effectors that enhance the protein's activity are referred to as ''allosteric activators'', whereas those that decrease the protein's activity are called ''allosteric inhibitors''. The term ''allostery'' comes from the Greek ''allos'', "other," and ''stereos'', "space," referring to the regulatory site of an allosteric protein's being separate from its active site. Allosteric regulation is a natural example of feedback control.
activator
(biology) any agency bringing about activation
four-step enzyme-mediated reaction sequence or metabolic pathway (A->B->C->D)
series of linked reactions, beginning with a particular reactant and terminating with an end product
Intermediate Compound
(chemistry) a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight
end product
a chemical substance formed as a result of a chemical reaction
feedback inhibition
A cellular control mechanism in which an enzyme that catalyzes the production of a particular substance in the cell is inhibited when that substance has accumulated to a certain level, thereby balancing the amount provided with the amount needed.
ADP-adenosine diphosphate
nucleotide with two phosphate groups that can accept other another phosphate group and become ATP
ATP-adenosine triphosphate
nucleotide with three phosphate groups. The breakdown of ATP into ADP+P makes energy available for energy-requiring processes in cells
chemical energy
energy associated with the interaction of atoms in a molecule
chemiosmosis
Process by which mitochondria and chloroplast use the energy of an electron transport chain to create a hydrogen ion gradient that drives ATP formation
coenzyme
nonprotein organic molecule that aids the action of the enzyme to which it is loosely bound
cofactor
nonprotein adjunct required by an enzyme in order to function; many cofactors are metal ions, others are coenzymes
competitive inhibition
form of enzyme inhibition where the substrate and inhibitor are both able to bind to the enzyme's active site. Only when the substrate is at the active site will product form
coupled reactions
reactions that occur simultaneously; one is an exergonic reaction that releases energy and the other is an endergonic reaction that requires an input of energy in order to occur
denatured
loss of an enzyme's normal shape so that is no longer functions; caused by a less than optimal pH and temperature
electron transport chain
passage of electrons along a series of membrane-bound electron carrier molecules from a higher to lower energy level; the energy released is used for the synthesis of ATP
energy
capacity to do work and bring about change; occurs in a variety of forms
energy of activation
energy that must be added in order for molecules to react with one another
entropy
measure of disorder or randomness
enzyme inhibition
means by which cells regulate enzyme activity; may be competitive or noncompetitive inhibition
free energy
useful energy in a system that is capable of performing work
heat
type of kinetic energy; captured solar energy eventually dissipates as heat in the environment
induced fit model
change in the shape of an enzyme's active site that enhances the fit between the active site and its substrates
kinetic energy
energy associated with motion
law of thermodynamics
two laws explaining energy and its relationships and exchanges. The first, also called the "law of conservation," says that energy cannot be created or destroyed but only be changed from one form to another; the second says that energy cannot be changed from one form to another without a loss of usable energy
mechanical energy
a type of kinetic energy, such as walking or running
metabolism
all of the chemical reactions that occur in a cell during growth and repair
NAD+ (nicotinamide adenine dinucleotide)
coenzyme of oxidation-reduction that accepts electrons and hydrogen ions to become NADH+H+ as oxidation of substrates occurs. During cellular respiration NADH carries electrons to the electron transport chain in mitochondria
NADP+(nicotinamide adenine dinucleotide phosphate)
coenzyme of oxidation-reduction that accepts electrons and hydrogen ions to become NADPH + H+. During photsynthesis, NADPH participates in the reduction of carbon dioxide to a carbohydrate
oxidation
loss of one or more electrons from an atom or molecule; in biological systems, generally the loss of hydrogen atoms
potential energy
stored energy as a result of location or spatial arrangement
product
substance that forms as a result of a reaction
reactant
substance that participates in a reaction
reduction
gain of electrons by an atom or molecule with a concurrent storage of energy; in biological systems, the electrons are accompanied by hydrogen ions
ribozyme
RNA molecule that can catalyze chemical reactions
vitamin
essential requirement in the diet, needed in small amounts. Vitamins are often part of coenzymes