Metabolic Pathways Flashcards
What are metabolic pathways
Metabolic pathways are integrated and controlled pathways of enzyme-catalysed reactions within a cell. Metabolic pathways can have reversible steps,irreversible steps and alternative routes.
What is an anabolic reaction
Build up large molecules from small molecules and require energy.
Catabolic reactions
Break down large molecules into smaller molecules and release energy.
Examples of membrane proteins
Protein pores- allows ions to diffuse across the membrane.
Pumps- transport molecules across membranes and often require energy, provided by ATP.
Enzymes are embedded in membranes
What are metabolic pathways controlled by
Presence or absence of particular enzymes.
Regulation of the rate of reaction of key enzymes.
When does induced fit occur
Induced fit occurs when the active site changes shape to better fit the substrate after the substrate binds.
What happens once an induced fit reaction is complete
The products have a low affinity for the active site and are released.
What does an enzyme lower
An enzyme lowers its activation energy by forming an enzyme-substrate complex that accelerated the rate of reaction.
What do enzymes provide
Enzymes provide an alternative path for reactions allowing a smaller Ea which means they can take place at a lower temperature.
What does a competitive inhibitor do
Binds directly to the active site, preventing substrate molecules binding.
Competitive inhibition….
Can be reversed by increasing the substrate concentration.
What does a non-competitive inhibitor do
Binds to an area on the enzyme away from the active site, this changes the shape of the active site, preventing the substrate from binding.
Non-competitive inhibition…..
Cannot be reversed by increasing substrate concentration
When does feedback inhibition occur
Occurs when the end-product in the metabolic pathway reaches a critical concentration.
What does the end product do in feedback inhibition
Inhibits an earlier enzyme, blocking the pathway, and so prevents further synthesis of the end-product.
