Enzymes Flashcards
What do enzymes do?
All enzymes, though through varying reaction mechanisms work in the same basic way, by lowering the activation energy for a reaction. Allowing reactions to occur at temperatures below 40°C allowing complex, delicate organic molecules to exist.
What is an enzyme?
A globular tertiary protein that speeds up a chemical reaction without itself undergoing any change. (Are biological catalysts)
What is activation energy?
The energy needed for a reaction to occur.
What is “the active site” and it’s function in an enzyme?
This is part of the overall 3D shape of the enzyme into which a substrate can fit. This site is how an enzyme works and can be easily deformed by pH and temperature changes.
What does the induced fit hypothesis suggest?
This suggests that the active site is a flexible structure which moulds itself around a range of similar substrate shapes as they enter the active site meaning that each enzyme can react with a wider range of substrate molecules.
What is the first stage in the way enzymes work?
An enzyme and substrate collide.
What is the second stage in the way enzymes work?
The shape of the enzyme ensures the substrate moves across the enzymes surface until it enters the active site.
What is the third stage in the way enzymes work?
As it enters the active site the flexible shape of the active site moles itself around the substrate forming an enzyme-substrate complex.
What is the fourth stage in the way enzymes work?
When the enzyme-substrate complex is formed the activation energy is lowered and the reaction occurs.
What is the fifth stage in the way enzymes work?
After the reaction the substrate changes in some way. As a result of which it no longer fits the active site and falls out as a product.
What does Kinetic Theory state and how is this relevant to enzymes.
That for a chemical reaction to occur molecules have to collide. Enzyme and substrate molecules will collide when they are in solution.
By extension of the Kinetic Theory what does a Enzyme-Substrate reaction require?
Movement requires energy which is provided in the form of latent heat from the environment.
How does heat affect a enzyme-substrate reaction.
The more heat there is, the more collisions and therefore the more product is formed so the reaction goes faster.
How can the rate of collisions between enzymes and substrate be sped up?
1 - Temperature increase
2 - Increase in enzyme concentration
3 - Increase in substrate concentration
Describe the general trend seen between temperature and rate of reaction.
They are directly proportional as on average (between 0°C and 40°C) every 10°C rise causes the reaction rate to double.
What happens to the graph of Rate of reaction against temperature as it approaches 40°C
The gradient of the graph begins to decrease as the active sites are beginning to get full.
What happens to the graph of Rate of reaction against temperature when it hits 40°C
The rate of reaction is at its maximum (gradient is 0) as all active sites are fully occupied. So the enzyme concentration has become the limiting factor.
What happens to the graph of Rate of reaction against temperature above 40°C
The rate of reaction falls sharply as hydrogen and then ionic bonds start to break, denaturing the enzyme.
Describe the general shape of a graph of Enzyme concentration against rate of reaction.
It increases in direct proportion and eventually levels off when substrate concentration becomes a limiting factor.
Explain the initial direct proportionality seen in a graph of enzyme concentration against rate of reaction.
Because the collision rate increases between the enzyme and substrate.
How can the rate be further increased after levelling off in a enzyme concentration against rate of reaction graph
It can be further increased by increasing the substrate concentration.
Describe the general shape of a substrate concentration vs rate of reaction graph.
It increases in direct proportion and eventually levels off when enzyme concentration becomes a limiting factor.
