Control of Metabolic Pathways Flashcards
Describe the control of metabolic pathways?
Metabolic pathways are controlled by the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes.
Explain ‘Induced fit’?
- Substrate molecules that have a similar shape but not complementary to the active site of a specific enzyme may still have some affinity and able to react.
- Induced fit occurs when the active site changes shape to better fit the substrate after the substrate binds.
Orientation of active site and substrate molecules.
The substrate molecule(s) have a high affinity to the active site and the subsequent products have a low affinity, allowing them to leave the active site.
Explain the presence of a substrate and removal of products on metabolic reactions.
Some metabolic reactions are reversible and the presence of a substrate or removal of a product will drive a sequence of reactions into a particular direction.
Define ‘competitive inhibitors’?
Competitive inhibitors bind at the active site preventing the substrate from binding.
How can competitive inhibition be reversed?
Competitive inhibition can be reversed by increasing substrate concentration.
Define ‘non-competitive inhibitors’?
Non-competitive inhibitors bind away from the active site but change the shape of active site preventing the substrate from binding. Non-competitive inhibition cannot be reversed by increasing substrate concentration.
Define ‘feedback inhibition’?
Feedback inhibition occurs when the end-product in the metabolic pathway reaches a critical concentration. The end-product then inhibits an earlier enzyme, blocking the pathway, preventing any further synthesise of the end-product.
