Enzymes Flashcards
1
Q
What is an enzyme?
A
- an enzyme is a protein that functions as a biological catalyst
2
Q
What does an enzyme do?
A
- they can speed up chemical reactions
- enzymes can build up or break down complex substances
3
Q
What is the lock and key hypothesis?
A
- it refers to enzyme specifity
4
Q
What is the lock and what is the key?
A
- the enzyme is the lock
- substrate is the key
5
Q
How does the lock and key hypothesis relate to enzyme action?
A
- the substrate binds to the active site of the enzyme, forming an enzyme-substrate complex
- products are then formed
- they are changed and thus no longer fit into the active site of the enzyme
- thus, they break off the enzyme
6
Q
How does a chemical reaction occur?
A
- in a chemical reaction
- the reactants collide with each other in the correct orientation and energy
7
Q
What is activation energy?
A
- activation energy is the energy required to make substances react
- it represents an energy barrier that has to be overcome for a reaction to occur
- activation energy can be supplied by heating the reactants
8
Q
How do enzymes speed up chemical reactions?
A
- they lower the activation energy needed for a reaction to start
9
Q
What are the characteristics of enzymes?
A
- enzymes remain chemically unchanged after catalysing a reaction
- thus they are required in minute amounts
- due to their active sites being only complementary to one substrate
- enzymes are specific in action
10
Q
What are some factors affecting the rate of an enzyme-catalysed reaction?
A
- temperature
- pH
11
Q
How does temperature affect enzyme-catalysed reactions?-
A
- at low temperatures, enzymes are inactive
- however, this is reversible and can be fixed by increasing the temperature which will cause more successful collisions to happen
- at optimum temperature, enzyme reaction rate is at its highest
- reaction rate doubles every 10 degrees until the optimum is met
- beyond the optimum, the enzyme is denatured
- denaturation is irreversible and causes an enzyme to lose its 3-d shape
- thus it loses its function
12
Q
How does pH affect an enzyme catalysed reaction?
A
- enzymes have an optimum pH
- it is the pH at which enzyme activity is at its maximum
- thus, any pH that deviates from the optimum will cause enzyme activity to decrease or denature an enzyme at extreme pH
- denaturation is irreversible
- even when the pH is back to its optimum, a denatures enzyme will not get its 3-d shape back and regain its functions
