Topic 3 Vocabulary
Activation Energy: The amount of energy needed for a reaction to happen.
Active Site: A specific region on an enzyme where the substrate binds and the reaction takes place.
Amylase: An enzyme that catalyzes the extracellular breakdown of starch.
Catalase: An enzyme that catalyzes the intracellular breakdown of hydrogen peroxide into oxygen and water.
Catalyst: A substance that increases the rate of reaction, often by offering an alternative reaction pathway with a lower activation energy. It is unchanged at the end of the reaction.
Colorimeter: A light-sensitive device that measures the absorbance or transmission of certain wavelengths of light by a solution. A colorimeter can be used to investigate the rate of a reaction that involves color changes.
Competitive Inhibitor: A molecule that binds to the active site of an enzyme and prevents the substrate from binding.
Enzyme: A globular protein molecule that acts as a biological catalyst and increases the rate of biochemical reactions. Some enzymes work intracellularly, and others work extracellularly.
Enzyme/Substrate Complex: The temporary complex formed when the substrate binds to the active site of the enzyme.
Extracellular Enzyme: An enzyme that is secreted by cells and functions outside of cells, e.g., amylase.
Extracellular Reaction: A reaction that occurs outside of cells, e.g., in the tissue fluid.
Immobilized Enzymes: Enzymes that are attached to an inert, insoluble material over which the substrate passes and the reaction takes place.
Induced-Fit Hypothesis: A model of enzyme action that describes how enzymes undergo subtle conformational changes which exert a strain on bonds in the substrate.
Intracellular Enzyme: An enzyme that acts within cells, e.g., catalase.
Intracellular Reaction: A reaction that occurs within cells.
Lock and Key Hypothesis: A model of enzyme action that describes how the enzyme will only fit a substrate that has the correct complementary shape to the active site.
Michaelis-Menten Constant (Km): A value that indicates how strong the affinity between an enzyme and its substrate is.
Non-Competitive Inhibitor: An inhibitor that binds to a part of an enzyme that is not the active site (an allosteric site) and prevents the enzyme from functioning.
Substrate Specificity: The ability of an enzyme to catalyze only a specific reaction or set of reactions which have substrates complementary to the active site of the enzyme.
Vmax: The maximum reaction rate.