8.1 Metabolism (HL) Flashcards
Metabolism
The sum total of all reactions that occur within an organism in order to maintain life
What are metabolic pathways?
When chemical changes result from a series of reactions with each step controlled by a specific enzyme
What are two types of metabolic pathways?
Cycles and chains
How do enzymes help?
They lower the activation energy for reactions they catalyze
Why do metabolic pathways help?
They allow for greater level of regulation as chemical change is controlled by numerous intermediates
Inhibitors
Chemicals that reduce rate of enzymatic activity. They are specific and work at low concentrations
Examples of inhibitors
Many drugs and poisons are inhibitors of enzymes in the nervous system. They block but don’t destroy
Competitive inhibitors
Compete WITH substrate for active site. Action of enzyme is proportionate to its concentration
Do competitive inhibitors resemble substrate structure?
Yes
Can effect of competitive inhibitor be reduced by increasing substrate concentration?
Yes. However it can reach or level close to the maximum rate of reaction if the inhibitor wasn’t there
Non-competitive inhibitors
Bind to allosteric (another site) on enzyme
What happens to active site with non-competitive inhibitors?
The active site gets altered and substrate cannot attach or react
Can effect of non-competitive inhibitor be reduced by increasing substrate concentration?
Not really. Rate of reaction decreases as there are fewer functional active sites for reaction. Max. rate of reaction is also reduced.
End-product inhibition
When the end product of the last enzyme in the chain acts as an inhibitor to an enzyme in the beginning to stop the reaction. It binds to the allosteric site and causes enzyme to change shape
Benefits of end-product inhibition
- Used to regulate metabolic pathways, switching on and off whenever required
- Uses its own products so its efficient
