Metabolic Pathways Flashcards
What are metabolic pathways?
Metabolic pathways are integrated and controlled pathways of enzyme-catalysed reactions within a cell. They can have reversible steps, irreversible steps and alternative routes.
Name the two types of reactions within metabolic pathways.
Catabolic and anabolic.
Describe anabolic reactions.
Anabolic reactions build up large molecules from small molecules and require energy.
Describe catabolic reactions.
Catabolic reactions break down large molecules into smaller molecules and release energy.
What is embedded in membranes?
Protein pores, pumps and enzymes.
How are metabolic pathways controlled?
They are controlled by the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes.
How do induced fit and the active site of an enzyme affect activation energy and affinity of the substrate and products for the active site?
If the active site changes shape the substrate and products will have a lower affinity for the enzyme.
When does induced fit occur?
Induced fit occurs when the active site changes shape to better fit the substrate after the substrate binds.
Describe the affinity that the substrate and products have for the active site.
The substrate molecule(s) have a high affinity for the active site and the subsequent products have a low affinity, allowing them to leave the active site.
Describe competitive inhibition.
Competitive inhibitors bind at the active site preventing the substrate from binding. This can be reversed by increasing substrate concentration.
Describe non-competitive inhibition.
Non-competitive inhibitors bind away from the active site but change the shape of the active site preventing the substrate from binding. This cannot be reversed by increasing the substrate concentration.
Describe feedback inhibition.
Feedback inhibition occurs when the end-product in the metabolic pathways reaches a critical concentration. The end-product then inhibits a earlier enzyme, blocking the pathway, and so prevents further synthesis of the end-product.
