4.1-4 Enzymes Flashcards
1
Q
What do enzymes do?
A
- increase the rate of reaction by lowering the activation energy of the reaction they catalase
2
Q
What is the active site?
A
- the area of the enzyme where the reaction with the substrate takes place
3
Q
What is enzymes relation to substrates?
A
- enzymes are specific to substrates they bind to meaning that only one type of substrate fits into the active site of the enzyme
4
Q
What happens when the enzyme and substrate form a complex?
A
- the structure of the enzyme is altered so that the active site of the enzyme fits around the substrate
- this is called the induced fit model
5
Q
What are the four factors effecting the rate of enzyme controlled reactions?
A
- enzyme concentration
- enzyme pH
- temperature
- substrate concentration
6
Q
How does enzyme concentration effect the rate of reaction?
A
- the rate of reaction increases as enzyme concentration increases as there are more active sites for substrates to bind to
- increasing enzyme concentration beyond a certain point has no effect on the rate of reaction as there are more active sites than substrates so substrate becomes the limiting factor
7
Q
How does substrate concentration effect the rate of reaction?
A
- as concentration of substrate increases, the rate of reaction increases as more enzyme-substrate complexes are formed
- beyond a certain point the rate of reaction no longer increases as enzyme concentration becomes the limiting factor
8
Q
How does temperature effect the rate of reaction?
A
- rate of reaction increases up to the optimum temperature, which the temperature at which enzymes work at their maximum rate
- rate of reaction decreases above the optimum temperature as enzymes can denature
9
Q
What is an inhibitor?
A
- a substance which slows down or stops a reaction by affecting the binding of substrate to enzymes
- can be reversible or irreversible
10
Q
Examples of irreversible inhibitors are …
A
- heavy metal ions such as mercury and silver which cause disulphide bonds within the protein structure to break, as a result causing the shape of active site to change, thus affecting protein activity
- cyanide which is nerve gas that covalently binds to the active site, therefore preventing the binding of the substrate
11
Q
What in an reversible inhibitor?
A
- bind to the active site through hydrogen bonds and weak ionic interactions therefore they do not bind permanently
- can either be competitive or non-competitive
12
Q
What are competitive inhibitors?
A
- are similar in structure to the substrate molecule therefore they bind to the active site of the enzyme, decreasing its activity as they compete with substrate for the enzyme
- the amount of product formed remains the same, however the rate at which product formation occurs decreases
13
Q
What is the effects that occur in the change of concentration in the competitive inhibitors?
A
- the high the concentration of competitive inhibitor the lower the reaction rate
- increasing the substrate reverses the effect of competitive inhibitors by out-competing them
14
Q
What are non-competitive inhibitors?
A
- it binds at another site on the enzyme known as the allosteric site
- binding of the non-competitive inhibitors changes the shape of the active site therefore preventing the binding of the substrate
- increasing the concentration of substrate has no effect on non-competitive inhibition
15
Q
Examples of inhibitors …
A
- drugs
- penicillin which is used to fight bacterial infections, it is an inhibitor of enzyme transpeptidase which plays an important role in cell wall formation
- ritonavir which is an antiretroviral drug used to treat HIV which inhibits HIV protease which is responsible for assembly of new viral particles and spread of infection
