| A | B |
|---|
| activation energy | amount of energy required to start a chemical reaction |
| active site | site on an enzyme that attaches to a substrate |
| allosteric enzyme | an enzyme whose shape can be altered by the binding of a signal molecule to its surface |
| autotroph | organism that obtains energy from sunlight or chemicals |
| biochemical pathway | series of enzyme-catalyzed reactions that perform a specific function |
| catalysis | process of increasing a chemical reaction rate through the action of a catalyst |
| catalyst | material that speeds up a chemical reaction without being used itself |
| cellular respiration | process by which living things obtain energy from the bonds of food molecules |
| chemical reaction | process by which the atoms of one or more molecules are rearranged to form molecules of one or more new substances |
| chemosynthesis | production of organic compounds using energy contained in inorganic molecules |
| closed system | in thermodynamics, a system that allows no energy or matter to leave |
| coenzyme | nonprotein molecule that assists an enzyme in carrying out a reaction |
| coupled reaction | endergonic reaction that is driven by the splitting of ATP molecules |
| endergonic reaction | reaction that absorbs free energy |
| energy | capacity for doing work, often described as the ability to make things move or change |
| entrophy | amount of disorder in a system; amount of unavailable energy in a system |
| enzyme | protein that catalyzes a chemical reaction |
| exergonic reaction | a reaction that releases free energy |
| feedback inhibition | negative feedback mechanism in which the end product of a metabolic pathway inhibits an enzyme that catalyzes a reaction previous in the pathway |
| first law of thermodynamics | law that states energy cannot be created or destroyed, but can only be converted from one form to another |
| free energy | amount of energy available for work (ex. to drive cell activities) |
| heterotroph | organism that cannot make its own food |
| kinetic energy | energy of an object due to its motion |
| metabolism | sum of all chemical processes occurring in an organism |
| NAD+ | nicotinamide adenine dinucleotide; oxidized form of a coenzyme that acts as an electron carrier in oxidation-reduction reactions |
| NADH | reduced form of NAD+ |
| open system | in thermodynamics, a system that exchanges matter and energy with its surroundings |
| oxidation | loss of electrons by an atom or molecule |
| oxidation-reduction reaction | chemical reaction in which electrons are passed from one atom or molecule to another |
| photosynthesis | process by which organisms use light energy to produce ATP and other organic molecules from inorganic molecules |
| potential energy | the energy an object has because of its position |
| product | new substance formed as a result of a chemical reaction |
| reactant | substance that is the starting material in a chemical reaction |
| reduction | gain of electrons by an atom or molecule |
| second law of thermodynamics | law that states that disorder increases continually in a closed system |
| substrate | the molecule on which an enzyme acts |
| system | in science, a collection of related objects that can be studied, such as an organism |
| thermodynamics | study of energy transformations |
