Metabolic pathways Flashcards
What are metabolic pathways
Metabolic pathways are integrated and controlled pathways of enzyme- catalysed reactions within a cell.
describe MP steps
Metabolic pathways can have reversible, irreversible and alternative routes.
Describe the reactions within a MP
Reactions within metabolic pathways
• Anabolic reactions involve the building up of large molecules from small molecules and require energy.
• Catabolic reactions breakdown large molecules into smaller molecules and release energy.
How are MP controlled
Metabolic pathways are controlled by the presence or absence of key enzymes.
Factors that control the rate of enzyme activity such as temperature, pH, substrate concentration and inhibition will also regulate the rate of a metabolic pathway
Describe induced fit
When a substate binds to the active site, the active site will change shape. This is to allow the active site to better fit the substrate after the substrate binds. This is known as the induced fit.
Why is a substrate attracted to active sites
Substrate molecules have high affinity for the active site which allows the substrate to bind easily.
How can products leave
Product molecules have a low affinity for the active site, and this allows the product(s) to leave the active site and allows the active site to bind again with another substrate molecule.
Some metabolic pathways are reversible and the presence of a substrate or the removal of a product will drive a sequence of reactions in a particular direction.
Describe competitive inhibitors
Competitive inhibitors bind at the active site preventing the substrate from binding. Competitive inhibition can be reversed by increasing the substrate concentration
Describe non competitive inhibitors
Non-competitive inhibitors bind away from the active site but change the shape of the active site preventing the substrate from binding. This type of inhibition cannot be reversed by increasing the substrate concentration.
Describe feedback inhibition
Feedback inhibition
Feedback inhibition occurs when the end-product in the metabolic pathway reaches critical concentration. The end-product inhibits an earlier enzyme, blocking the pathway, and so prevents further synthesis of the end product.
