OCR ALevel Biology - Module 2 - Definitions - Topic 2.4 : Enzymes Flashcards
What is activation energy?
The amount of energy needed for a reaction to happen.
What is an active site?
A specific region on an enzyme where the substrate binds and the reaction takes place.
What is amylase?
An enzyme that catalyses the extracellular breakdown of starch.
What is catalase?
An enzyme that catalyses the intracellular breakdown of hydrogen peroxide into oxygen and water.
What is a coenzyme?
A type of cofactor that is bound loosely to an enzyme with weak interactions.
What are cofactors?
A non-protein molecule that is needed for the effective functioning of an enzyme.
What is a competitive inhibitor?
A molecule which binds to the active site of an enzyme and prevents the substrate from binding.
What is cyanide (CN-)?
A metabolic poison which acts as an irreversible inhibitor of cytochrome oxidase and hence preventing respiration.
What is end-product inhibition?
A method of enzyme inhibition where the product of an enzyme controlled reaction can bind to the enzyme and prevent it from working.
What is an enzyme?
A biological catalyst used to speed up the rate of biochemical reactions without being used up or permanently altered.
What is an enzyme-product complex?
The temporary complex formed after the enzyme has catalysed the reaction but before the products have left the active site of the enzyme.
What is an enzyme-substrate complex?
The temporary complex formed when the substrate binds to the active site of the enzyme.
What is an extracellular reaction?
A reaction that occurs outside of cells.
What is an inactive precursor?
An inactive form of an enzyme that cannot carry out its function until it is activated.
What is the induced fit hypothesis?
A model of enzyme action that describes how once a specific substrate binds to the active site, the enzyme undergoes subtle conformational changes to fit the substrate better.
What is an intracellular reaction?
A reaction that occurs within cells.
What is the 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.
What is metabolism?
The sum of all the chemical reactions taking place in a cell.
What is a non-competitive inhibitor?
An inhibitor which binds to a different part of an enzyme known as the allosteric site and prevents the enzyme from functioning.
What is a prosthetic group?
A type of cofactor that is bound tightly to an enzyme with strong interactions.
What is 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.
What is the temperature coefficient (Q10)?
A method of calculating an increase in reaction rate after a 10°C temperature increase - calculated using the following equation: Q10 = R2/R1.
What is trypsin?
An enzyme that catalyses the extracellular breakdown of proteins.
