Chapter 5 Key Terms Flashcards
The amount of energy that reactants must absorb before a chemical reaction will start. An enzyme lowers the** of a chemical reaction, allowing it to proceed faster.
Activation Energy
The part of an enzyme molecule where a substrate molecule attaches—typically, a pocket or groove on the enzyme’s surface.
Active Site
The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring the input of energy (often as ATP).
Active Transport
The amount of energy that raises the temperature of 1 g of water by 1°C. Commonly reported as Calories, which are kilocalories (1,000 calories).
calorie
Energy stored in the chemical bonds of molecules; a form of potential energy.
Chemical Energy
An increase or decrease in the density of a chemical substance within a given region. Cells often maintain concentration gradients of hydrogen ions across their membranes. When a gradient exists, the ions or other chemical substances involved tend to move from where they are more concentrated to where they are less concentrated.
Concentration Gradient
The principle that energy can be neither created nor destroyed.
Conservation of Energy
The spontaneous movement of particles of any kind down a concentration gradient, that is, movement of particles from where they are more concentrated to where they are less concentrated.
Diffusion
The movement of materials from the external environment into the cytoplasm of a cell via vesicles or vacuoles.
Endocytosis
A measure of disorder, or randomness. One form of disorder is heat, which is random molecular motion.
Entropy
A molecule (usually a protein, but sometimes RNA) that serves as a biological catalyst, changing the rate of a chemical reaction without itself being changed in the process.
Enzyme
A chemical that interferes with an enzyme’s activity by changing the enzyme’s shape, either by plugging up the active site or by binding to another site on the enzyme.
Enzyme Inhibitor
The movement of materials out of the cytoplasm of a cell via membranous vesicles or vacuoles.
Exocytosis
The passage of a substance across a biological membrane down its concentration gradient aided by specific transport proteins.
Facilitated Diffusion
The amount of kinetic energy contained in the movement of the atoms and molecules in a body of matter. ***is energy in its most random form.
Heat
In comparing two solutions, referring to the one with the greater concentration of solutes.
Hypertonic
In comparing two solutions, referring to the one with the lower concentration of solutes.
Hypotonic
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.
Induced Fit
Having the same solute concentration as another solution.
Isotonic
The total of all the chemical reactions in an organism.
Metabolism
The diffusion of water across a selectively permeable membrane.
Osmosis
The diffusion of a substance across a biological membrane without any input of energy.
Passive Transport
Cellular “eating”; a type of endocytosis whereby a cell engulfs large molecules, other cells, or particles into its cytoplasm.
Phagocytosis
A substance that is dissolved in a liquid (which is called the solvent) to form a solution.
Solute
(1) A specific substance (reactant) on which an enzyme acts. Each enzyme recognizes only the specific substrate of the reaction it catalyzes. (2) A surface in or on which an organism lives.
Substrate
