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the part of an enzyme or antibody where the chemical reaction occurs

ADP (adenosine diphosphate)

molecule formed from the breaking off of a phosphate group for ATP, results in a release of energy that is used for biological reaction

ATP (adenosine triphosphate)

energy storing molecule in cells composed of an adenosine molecule, a ribose sugar and 3 phosphate groups energy is stored in the molecules chemical bonds and can be used quickly and easily by cells

ATP synthase complex

a special protein complex embedded in the thylakoid membrane that allows H+ ions to escape from the lumen and uses the resulting energy to generate or make ATP

chemical energy

potential energy stored in chemical bonds of molecules


in chloroplasts and mitochondria, a process in which the movement of protons down their concentration gradient across a membrane is coupled to the synthesis of ATP


a small molecule (not a protein but sometimes a vitamin) essential for the activity of some enzymes


a substance (as a coenzyme) that must join with another to produce a given result

competitive inhibition

The process of a substance reducing the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics.

coupled reactions

when the energy released by an exergonic reaction is used to drive an endergonic reaction


when a protein loses its natural shape; destroyed by high temps that change their pH and can no longer function properly

electron transport chain

A sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP.

endergonic reaction

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings.


an exertion of force

energy of activation

The amount of energy that reactants must absorb before a chemical reaction will start


A quantitative measure of disorder or randomness, symbolized by S.


any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions

enzyme inhibition

Process by which a substance known as an inhibitor binds to an enzyme and decreases it's activity

exergonic reaction

A spontaneous chemical reaction in which there is a net release of free energy.

feedback inhibition

A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

free energy

The portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system.


a form of energy that is transferred by a difference in temperature

induced fit model

The model of the enzyme that shows the substrate binding to the active site and the active site altering slightly is the

kinetic energy

the mechanical energy that a body has by virtue of its motion

laws of thermodynamics

1) energy can not be created or destroyed, only converted from one form to another, 2) each time you convert one form of energy to another, some energy is converted to a non-usable form (more energy efficient to consume plants because they exist very close to the initial source of energy), 3) also called law of conservation

mechanical energy

kinetic or potential energy associated with the motion or position of an object

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).


set of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes

NAD + (nicotinamide adenine dinucleotide)

Nicotinamide adenine dinucleotide, a coenzyme present in all cells that helps enzymes transfer electrons during the redox reactions of metabolism.

NADP + (nicotinamide adenine dinucleotide phosphate)

one of the carrier molecules that transfers high-energy electrons from chlorophyll to other molecules

noncompetitive inhibition

the act of binding to another part of an enzyme, causing the enzyme to change shape and making the active site less effective


the loss of electrons from a substance involved in a redox reaction


The transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation.

potential energy

energy stored due to an object's position or arrangement


a chemical substance formed as a result of a chemical reaction


a chemical substance that is present at the start of a chemical reaction


any process in which electrons are added to an atom or ion (as by removing oxygen or adding hydrogen)


reactant of an enzyme-catalyzed reaction


any of a group of organic substances essential in small quantities to normal metabolism

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