B1.2.3 + B1.2.4 - enzymes Flashcards
What are enzymes made of?
Protein
What are enzymes?
They are biological catalysts. They speed up a reaction without being used up.
What types of reactions are enzymes involved in?
They can build larger molecules from smaller ones (e.g in protein synthesis)
They can break down larger molecules into smaller ones (e.g in digestion)
What do enzymes look like?
Enzymes are made of protein and so are made up of long chains of amino acids which are folded up to form a specific shape.
What is the active site?
It is where molecules of other substances bind to the enzyme.
What is the substrate?
It is the molecule that binds to the enzyme
Why do enzymes only bind to one type of molecule?
Enzymes are highly specific.
The substrate must fit exactly into the active site and if it does not the molecule cannot bind.
What is the lock and key hypothesis?
The enzyme is like a lock and the substrate is like a key.
Only one key fits the lock and can be able to turn to open the door.
This is the lock and key hypothesis
What happens when the substrate binds to the enzyme?
An enzyme substrate complex is formed.
What factors affect enzymes?
Temperature
pH
Concentration of enzymes
Concentration of substrate
What is an optimum condition
The conditions in which the enzyme works best
How does temperature affect enzyme reactions?
At higher temperatures the enzyme and substrate molecules collide more often. So the higher the temperature the faster the reaction.
But if the temperature gets too high, the amino acid chains in the protein start to unravel, changing the shape of the active site so the enzyme is now denatured so the substrate can’t bind to it and the rate of reaction decreases .
Once all the enzyme molecules are denatured, the reaction stops.
How does pH affect enzyme controlled reactions?
Each enzyme has an optimum pH.
A change in pH affects the interactions between amino acids in a chain. Thus may make the enzyme unfold, changing the shape of the active site and the enzyme will become denatured.
How does substrate concentration affect the rate of enzyme controlled reactions?
The higher the substrate concentration the faster the rate of reaction.
But once all the enzyme molecules, the rate of reaction is at its maximum and any further increase in the number of substrate molecules will not increase the rate of reaction as there are no enzymes for them to bind to.
How does enzyme concentration affect enzyme controlled reactions?
The higher the enzyme concentration, the faster the rate of reaction. But this is limited by substrate concentration as if no new substrate molecules are added the reaction will stop.
