1.5 Enzymes Flashcards
What does the term ‘metabolism’ refer to?
All the reactions of the body. Organisms need to carry out metabolic reactions to survive.
What is the relationship between temperature and rate of reaction?
Rate of reaction increases as temperature does, however high temperatures can damage cells.
What is a catalyst?
A chemical that speeds up the rate of reaction and remains unchanged and reusable at the end of the reaction
What are enzymes?
Biological catalysts for metabolic reactions are called enzymes.
What is a substrate?
Any molecule that can have the reaction catalysed by an enzyme.
What is an enzyme’s ‘turnover number’?
The number of substrates an enzyme can catalyse in one minute.
What is the ‘active site’ of an enzyme?
The reactive part of an enzyme. A substrate will only bind with an active site if it is the correct shape, therefore every substrate will have a specific enzyme that it can bind with.
What factors can change the shape of an active site?
pH, temperature and the presence of inhibitors or cofactors.
What is activation energy?
The energy required to start a reaction. A reaction with a low activation energy will occur faster because there will be more molecules with sufficient energy to react. Enzymes catalyse reactions by lowering the activation energy required for a reaction to occur. This also allows for reactions to occur at lower temperatures.
What happens when an enzyme collides with the correct substrate?
It binds with the active site, forming an enzyme-substrate complex. The metabolic reaction occurs and an enzyme-product complex is formed. The product or products detach from the enzyme, leaving the enzyme to catalyse the same reaction again.
What is the lock-and-key hypothesis?
Scientists used to think enzymes worked like a lock and key; in this model each substrate is key that only fits a specific lock or enzyme. This model is based on an enzyme’s active site being rigid and permanently complementary to the shape of it’s substrate.
