Working Cell Vocabulary

energy
The capacity to do work (to move matter against an opposing force)
kinetic energy
The energy of motion, which is directly related to the speed of that motion. Moving matter does work by imparting motion to other matter.
conservation of energy
The principle that energy can neither be created nor destroyed.
potential energy
The energy stored by matter as a result of its location or spatial arrangement.
heat
The total amount of kinetic energy due to molecular motion in a body of matter. Heat is energy in its most random form
entropy
A quantitative measure of disorder or randomness.
chemical energy
Energy stored in the chemical bonds of molecules; a form of potential energy.
cellular respiration
The aerobic harvesting of chemical energy from organic fuel molecules
calorie
The amount of energy that raises the temperature of water by 1°C.

ATP
(adenosine triphosphate)An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive reactions in cells.
energy coupling
In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction.
phosphorylation
The transfer of a phosphate group to a molecule.

metabolism
The many chemical reactions that occur in organisms.
enzyme
A protein serving as a catalyst, a chemical agent that changes the rate of a reaction without being consumed by the reaction.
activation energy
The amount of energy that reactants must absorb before a chemical reaction will start
substrate
The reactant on which an enzyme works.
active site
The specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds.
induced fit
The interaction between a substrate molecule and the active site of an enzyme, which changes shape slightly to embrace the substrate and catalyze the reaction.
feedback regulation
A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

selective permeability
A property of biological membranes that allows some substances to cross more easily than others.
transport proteins
A membrane protein that helps move substances across a cell membrane
diffusion
The spontaneous tendency of a substance to move down its concentration gradient from a more concentrated to a less concentrated area.
facilitated diffusion
The spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients.
isotonic
Having the same solute concentration as another solution.
hypotonic
hypertonic
osmoregulation
The control of water balance in organisms living in hypertonic, hypotonic, or terrestrial environments.
osmosis
The diffusion of water across a selectively permeable membrane.
active transport
The movement of a substance across a biological membrane against its concentration or electrochemical gradient with the help of energy input and specific transport proteins.

endocytosis
The cellular uptake of macromolecules and particulate substances by localized regions of the plasma membrane that surround the substance and pinch off to form an intracellular vesicle
exocytosis
The cellular secretion of macromolecules by the fusion of vesicles with the plasma membrane.
phagocytosis
"Cellular eating"; a type of endocytosis whereby a cell engulfs a particle into its cytoplasm.
pinocytosis
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.