1.4 enzymes Flashcards
(24 cards)
what is a catalyst
a substance that speeds up a reaction without changing the substances produced or being changed itself.
what is an enzyme
proteins that have a very specific shape as a result of their primary, secondary, tertiary and quaternary structures. They act as biological catalysts and each enzyme will only catalyse a specific reaction or group of reactions.
what is specificity
the characteristic of enzymes that means that, as a result of the very specific shapes resulting from their tertiary and quaternary structures, each enzyme will only catalyse a specific reaction or group of reactions.
what is an anabolic reaction
is the reaction that builds up (synthesises) new molecules in a cell.
what is a catabolic reaction
is a reaction which breaks down substances within a cell.
what is metabolism
Metabolism is the sum of the anabolic and catabolic processes in a cell.
what is a metabolic chain
A metabolic chain (metabolic pathway) is a series of linked reactions in the metabolism of a cell.
what are intercellular enzymes
Intracellular enzymes are enzymes that catalyse reactions within the cell
what are extracellular enzymes
enzymes that catalyse reactions outside of the cell in which they were made.
what is activation energy
the energy needed for a reaction to get started.
what is a substrate
the molecule or molecules on which an enzyme acts.
what is the lock ad key hypothesis
the model that explains enzyme action by an active site in the protein structure that has a very specific shape. The enzyme and substrate slot together to form a complex as a key fits in a lock.
what Is an active site
is the area of an enzyme that has a specific shape into which the substrate(s) of a reaction fit.
what is the induced fit theory
is a modified version of the L+K hypothesis for enzyme action where the active site is considered to have a more flexible shape. Once the substrate enters the active site, the shape of that site is modified around it to form the active complex. Once the products have left the complex, the enzyme reverts to its inactive, relaxed form.
why is the initial rate of reaction taken
is the measure taken to compare the rates of enzyme controlled reactions under different conditions.
what is molecular activity
(turnover number) is the number of substrate molecules transformed per minute by a single enzyme molecule.
what is the temperature coefficient
(Q0) is the measure of the effect of temperature on the rate of a reaction.
what are enzyme exhibitors
are substances that slow down enzymes or stop them from working.
what are reversible inhibition
is 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 is often used to control reaction rates within a cell.
what are competitive inhibition
is 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 (affected by both inhibitor and substrate concentrations).
what are irreversible inhibition
is inhibition of the action of an enzyme that is permanent and cannot be undone. It is never used within cells to control the rate of reactions.
what are noncompetitive inhibition
is 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 the reaction (affected only by concentration of inhibitor).
what are regulatory enzymes
are enzymes that have a site separate to the active site where another molecule ca bind to have either an activating or inhibitory effect.
what are end-product inhibition
is a 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.
