Chapter 7- Enzymes (1) Flashcards
What is entropy?
A measure of the amount of energy which is unavailable to do work.
How do chemical reactions effect entropy?
It increases entropy
Entropy favours a reaction to increase what?
Disorder. The higher the entropy, the greater the disorder.
What is activation energy?
The initial energy needed to start a chemical reaction.
What often supplies the activation energy?
Thermal energy from cells
What do enzymes do to the activation energy of a reaction?
It decreases the activation energy of a reaction.
What is the definition of enzymes?
Enzymes are biological catalysts that speed up chemical reactions.
What does the active site do?
The active site has a specific binding site which binds to a specific substrate molecule.
Enzymes are a type of what?
Protein
How do enzymes increase the rate of production?
By reducing the activation energy
Enzymes catalyse a reaction by…
Stabilising the transition state.
What is the transition state?
Transition state is the highest activation energy on a reaction coordinate in which the molecule is partially reacted.
An enzyme is complementary to what in order for the reaction to take place?
The transition state. NOT THE SUBSTRATE.
What are the enzyme models?
1- Lock and key model
2- Induced fit model
Describe the lock and key model
- The shape of the enzyme active site and substrate fit together perfectly.
- The two shapes are considered rigid and fixed
Describe the induced fit model
- Binding of the substrate slightly changes the structure of the active site of the enzyme.
- The enzyme may also slightly distort the substrate.
What is enzyme kinetics?
How reaction velocity rates change with varying substrate concentration
In order to find out how velocity changes, what would you measure?
You would measure the rates of enzyme- catalysed reactions at different substrate and enzyme concentrations.
What is the reaction equilibrium?
Amount of product formed increases with time, until a time is reached where there is no net change in the concentration. This is the reaction equilibrium.
What is the Michaelis constant (Km)
Tells you the substrate concentration, at which half the enzyme is bound to the substrate.
What does the Michaelis constant (Km) indicate?
Indicates how well a substrate binds with a given enzyme.
What does a small Km indicate?
A small Km indicates that the enzyme only requires a small amount of substrate to become saturated.
What does a large Km indicate?
A large Km indicates the need for high substrate concentrations to become saturated.
What is Km important for?
If you want to try and inhibit enzymes in the body.
A large number of therapeutic drugs are enzyme inhibitors.
