1.4 Enzymes
Term 1: Metabolic reactions
Definition 1: Reactions that take place inside cells/living organisms.
Term 2: Metabolic pathway
Definition 2: Reactions that must occur in a specific sequence known as a metabolic pathway where the product of one reaction is a reactant of another.
Term 3: Anabolic Reactions
Definition 3: Simple molecules are built up into larger more complex molecules using more energy than they release.
Term 4: Catabolic Reactions
Definition 4: Large molecules are broken down into smaller molecules, releasing more energy than they use.
Term 5: Intracellular Enzymes
Definition 5: Exist in solution inside cells, e.g., Hydrolases in lysosomes and enzymes involved in glycolysis in the cytoplasm.
Term 6: Membrane bound Intracellular Enzymes
Definition 6: Attached to the inner mitochondrial membrane (cristae) and involved in ATP synthesis during aerobic respiration.
Term 7: Extracellular Enzymes
Definition 7: Act outside of cells; secreted from cells by exocytosis and catalyse extracellular reactions, e.g., digestive enzymes in the alimentary canal.
Term 8: Enzymes
Definition 8: Globular proteins with a specific 3D structure that act on substrate molecules which bind to the active site of the enzyme.
Term 9: Active site
Definition 9: A cleft on an enzyme molecule with a specific 3D shape into which a substrate molecule fits during a metabolic reaction.
Term 10: Biological catalyst
Definition 10: A protein produced by cells that speeds up the rate of a metabolic reaction without being used up itself.
Term 11: Enzyme Kinetics
Definition 11: Enzymes and substrates move in solution in a constant random motion due to their own kinetic energy (KE).
Term 12: Lock-and-Key Theory
Definition 12: The substrate is imagined as fitting into the active site of the enzyme, like a key fit into a lock. The shape of the lock and the key are specific and complementary to each other.
Term 13: Induced Fit Theory
Definition 13: The shape of the active site is not complementary to the shape of the substrate. So, the shape of that active site alters to bind to the substrate.
Term 14: Activation energy
Definition 14: The minimum energy that must be put into a chemical system for a reaction to occur.
Term 15: Buffers
Definition 15: Molecules that donate or accept protons to resist changes in pH.
Term 16: Vmax
Definition 16: maximum velocity - maximum rate of reaction.
Term 17: Enzyme Inhibitor
Definition 17: Any molecule or ion that reduces the rate of an enzyme controlled reaction.
Term 18: Competitive Inhibitors
Definition 18: Molecules that have a similar shape to the substrate and compete with the substrate for the active site.
Term 19: Non - competitive Inhibitors
Definition 19: Inhibitors work by binding to the enzymes at