2.1 Metabolic Pathways and their Control Flashcards
Define ‘metabolic pathway’
a series of integrated and controlled pathways of enzyme-catalysed reactions within a cell
What are the two types of metabolic pathway?
- Anabolic
- Catabolic
Describe an anabolic metabolic pathway
Builds up large molecules from small molecules and requires energy.
Describe an catabolic metabolic pathway
Breakdown large molecules into smaller molecules and releases energy.
Are all metabolic pathways irreversible?
No. They can be:
- Reversible
- Irreversible
- Alternative routes
State the three membrane proteins that are invovled in metabolic pathways?
- Pores
- Pumps
- Enzymes
How are metabolic pathways controlled?
the presence or absence of particular enzymes and by regulating the rate of reaction of key enzymes.
Define ‘activation energy’
The minimum amount of energy required for a chemical reaction to occur
e.g. striking a match on the box allows the match to light
Explain how enzymes affect activation energy
Enzymes lower the activitation energy allowing reactions to occur at lower temperatures
Define ‘induced fit’
When the substrate binds to an enzymes active site, the active site changes shape to better fit the substrate
What has a high affinity for an enzymes active site?
Substrates
What has a low affinity for an enzymes active site?
Products
How will a high substrate concentration affect an enzyme’s rate of reaction?
It will speed up the rate of reaction
Explain why having more substrates makes an enzyme reaction rate increase
More active sites are occupied so more substrates become products.
If a reaction is reversible having more product will do what?
Drive the reaction into reverse turning the product back into the substrates
State the three ways metaobolic pathways can be controlled?
- Competitive inhibition
- Non-competitive inhibition
- Feedback inhibition
Define ‘competitive inhibition’
A competitive inhibitor has a similar shape to the substrate and will bind at the active site preventing the substrate from binding.
How can competitive inhibition be reversed?
by increasing substrate concentration.
Define ‘non-competitive’ inhibition
A non-competitive inhibitor binds at an allosteric site on the enzyme.
This causes a permeant change in the shape of the active site preventing the substrate from binding
How can non-competitive inhibition be reversed?
It cannot be reversed by increasing substrate concentration.
Define ‘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, and so prevents further synthesis of the end-product.
Is feedback inihibition competitive or non-competitive?
It can be either
