Metabolic Pathways Flashcards
What are metabolic pathways?
Integrated and controlled pathways of enzyme-catalysed reactions within a cell.
What are the types of reactions within metabolic pathways?
Anabolic and catabolic
What is the function of anabolic pathways?
They build up large molecules from small molecules and they require energy.
What is the function of catabolic pathways?
To break down large molecules into smaller molecules and release energy.
How are metabolic pathways controlled?
By the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes.
How does induced fit occur?
When the active site changes shape to better fit the substrate after it binds.
How are the end-products allowed to leave the active site?
The end-product has a low affinity for the active site.
What are the factors affecting enzyme activity?
- Temperature
- pH
- Substrate concentration
- Enzyme concentration
- Inhibitors
What effect does increasing the substrate concentrations have on the enzyme activity?
It increases the activity to a point as more active sites become occupied.
What is the limiting factor when substrate concentration is increased?
The enzyme concentration.
What effect does increasing the enzyme concentration have on enzyme activity?
The activity increases until the enzyme concentration is large.
When is substrate concentration the limiting factor?
When the concentration of enzymes is increased.
Why are some metabolic reactions reversible?
Because the presence of a substrate or the removal of a product will drive a sequence of reactions in a particular direction.
How do competitive inhibitors prevent the substrate from binding to the active site?
By binding at the active site themselves.
How can competitive inhibition be reversed?
By increasing the substrate concentration.
How do non-competitive inhibitors prevent the substrate from binding to the active site?
By binding away from the active site but changing the shape of the active site.
When does feedback inhibition occur?
When the end-product in the metabolic pathway reaches a critical concentration.
How does end-product inhibition work?
The end-product inhibits an earlier enzyme, blocking the pathway, and so prevents further synthesis of the end-product.
What is an inhibitor?
A substance which slows down the rate of an enzyme controlled reaction.
