1.4. Enzymes - Key words Flashcards
Catalyst
Substance that speeds up a reaction without changing the substances produced or being changed itself
Enzymes
Proteins that have a very specific shape as a result of their structure. They act as biological catalysts and will only catalyse specific reactions
Specificity
Enzymes will only catalyse specific reactions due to their specific structure
Anabolic reaction
Reaction that builds up new molecules in a cell
Catabolic reaction
Reaction that breaks down substances within a cell
Metabolism
Sum of catabolic + anabolic processes in a cell
Metabolic chain (pathway)
Series of linked reactions in the metabolism of a cell
Intracellular enzymes
Enzymes that catalyse reactions within the cell
Extracellular enzymes
Enzymes that catalyse reactions outside of the cell in which they are made
Activation energy
Energy needed for a reaction to get started
Substrate
Molecule(s) on which the enzyme acts
Lock-n-key hypothesis
Substrate fits perfectly in enzyme’s active site creating a complex as a key fits a lock
Active site
Area of an enzyme that has a specific shape into which the substrate(s) of a reaction fit
Induced-fit hypothesis
Active site is considered to have a more flexible shape. The substrate fits the active site which is modified to form the complex. When products leave the complex the enzyme reverts shape
Initial rate of reaction
Measure taken to compare the rates of enzyme controlled reactions under different conditions
Molecular activity
Number of substrate molecules transformed per minute by a single enzyme molecule
Temperature coefficient (Q10)
Measure of the effect of temperature on the rate of a reaction
Enzyme inhibitors
Substances that slow down/stop enzymes from working
Reversible inhibition
Inhibition of the action of an enzyme by an inhibitor that does not permanently affect the functioning of the enzyme and can be removed from the enzyme. It’s often used to control reaction rates within a cell
Irreversible inhibition
Inhibition of the action of an enzyme that is permanent and cannot be undone. Never used within cells to control the rate of reactions
Competitive inhibition
Inhibition in which the inhibitor molecule is similar in shape to the substrate molecule and competes with it for the active site of the enzyme
Non-competitive inhibition
Inhibition in which the inhibitor does not compete for the active site but forms a complex with the enzyme or enzyme/substrate complex and changes the shape of the active site so it can no longer catalyse reaction
Regulatory enzymes
Enzymes that have a site separate to the active site where another molecule can bind to have either an activating or inhibitory effect
End-product inhibition
Control system in many metabolic pathways in which an enzyme at the beginning of the pathway is inhibited by one of the end products of the reaction
