1.4 Enzymes and Biological reactions Flashcards
Metabolism
All the organism’s chemical processes comprising anabolic and catabolic pathways
Metabolic pathway
A sequence of enzyme-controlled reactions in which a product of one reaction is a reactant to the next
Enzyme
A biological catalyst; a protein made by cells that alters the rate of a chemical reaction without being used up by the reaction
Catalyst
An atom or molecule that alters the rate of a chemical reaction without taking part in the reaction or being changed by it
Enzyme-substrate complex
Intermediate structure formed during an enzyme-catalysed reaction in which the substrate and enzyme bind temporarily, such that the substrates are close enough to react
Induced fit
The change in shape of the active site of an enzyme, induced by the entry of the substrate, so that the enzyme and substrate bind closely
Activation energy
The minimum energy that must be put into a chemical system for a reaction to occur
Biosensor
A device that combines a biomolecule, such as an enzyme, with a transducer, to produce an electrical signal which measures the concentration of a chemical.
Active site
A specific region on an enzyme where the substrate binds and the reaction takes place
Competitive inhibitor
A molecule which binds to the active site of an enzyme and prevents the substrate from binding.
Denaturation
Upon exposure to high temperatures or extremes of pH, the permanent change in the tertiary structure of an enzyme and the shape of its active site, preventing it from carrying out its cellular function (because the substrate can’t bind and enzyme-substrate complexes can’t form)
extracellular reaction
A reaction that occurs outside of cells
e.g. in mouth - saliva travels from salivary glands, through salivary duct, to the mouth, for amylase to break down starches
Immobilised enzymes
enzymes which are attached to an inert, insoluble material over which the substrate passes and the reaction takes place
Intracellular reaction
A reaction that occurs within cells.
Membrane-bound - synthesis of ATP on cristae of mitochondria
In solution - Synthesis of glucose in stroma of chloroplasts
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
Lysozyme
An enzyme found in tears and saliva that damages the cell walls of bacteria
Non-competitive inhibitors
An inhibitor which binds to a different part of an enzyme (known as the allosteric site), changes the shape of the enzyme and therefore the active site, preventing substrate from binding and enzyme from functioning.
substrate specificity
The ability of an enzyme to catalyse only a specific reaction or set of reactions which have substrates complementary to the active site of the enzyme
Diagram for enzyme lowering activation energy
Curve drawn with a lower activation energy under existing curve - energy state at beginning and end must be the same
