Key Area 6 Flashcards
What are metabolic pathways?
integrated, controlled and coordinated pathways of enzyme catalysed reactions in a cell
What 3 things can a metabolic pathways have?
Reversible steps, irreversible steps and alternative routes
What happens in a reversible metabolic pathway?
The presence of a substrate or removal of a product will drive a sequence of reactions in a particular direction
What 2 things can reactions within a metabolic pathway be?
- anabolic
- catabolic
What is an anabolic reaction?
A reaction which builds up large molecules from small molecules and requires energy
What is a catabolic reaction?
A reaction which breaks down large molecules into smaller molecules and releases energy
How are metabollic pathways controlled
By the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes
What does every chemical reaction inside a cell require?
Energy
What is the energy required for a chemical reaction to take place known as?
Activation Energy
How do enzymes work?
They lower the Activation Energy
What is an induced fit?
The active site changes slightly after a substrate binds to better fit the substrate
What do substrate molecules have for the active site?
High affinity
What do products have for the active site?
Low affinity
What happens to the rate of reaction as substrate concentration increases?
The rate of reaction increases until all the active sites of the enzyme are involved in the reaction
What happens to the rate of reaction as product concentration increases?
In most cases, the rate of reaction will decrease
What happens to the direction of reaction as substrate concentration increases?
There will be an increase in conversion towards the product
What happens to the direction of a reaction as a product concentration increases?
In most cases the direction of reaction will reverse and some product will be converted into intermediates of the reaction
If the product is used immediately or stored outside of the cell, the reaction will continue in the forward direction to ensure a continuous supply of product
What is control of metabolic pathways affected by?
Inhibition of enzymes
What are the 3 types of enzyme inhibition?
Competitive
Non- Competitive
Feedback
What will all types of inhibitor do?
Decrease the rate of an enzyme controlled reaction
What do competitive inhibitors do?
Bind at the active site preventing the substrate from binding
What do non - competitive inhibitors do?
Bind away from the active site but the shape of the active site will change, preventing the substrate from binding
What does feedback inhibition do?
Occurs when the end product in a metabolic pathway reaches a critical concentration
The end product then inhibits an earlier enzyme blocking the pathway and preventing further synthesis of end product.
How can competitive inhibition be reversed?
By increasing substrate concentration
Can non competitive inhibition be reversed by increasing substrate concentration?
No
