Unit 2 - Metabolism and Survival (Metabolic Pathways) Flashcards
(10 cards)
What are metabolic pathways?
A series of chemical reactions that start with a substrate and finish with an end product. Metabolic pathways are integrated and controlled enzyme-catalysed reactions within a cell. Metabolic pathways can have reversible, irreversible and alternative routes. Metabolic pathways are controlled by the presence or absence of key enzymes. Factors that control the rate of enzyme activity such as temperature and pH, will also regulate the rate of a metabolic pathway. 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.
What are anabolic reactions?
Requires energy and is used to build up large molecules from smaller ones (biosynthesis).
What are catabolic reaction?
Releases energy and is used to break down large molecules into smaller ones (degradation).
What can proteins in the cell membrane act as?
- Pores (allowing molecules to pass through).
- Pumps (allowing molecules to pass through the membrane. Requires energy, so the molecule is actively pumped inside or outside of the cell).
- Enzymes (catalysing chemical reactions).
What is an induced fit?
When a substrate 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.
What is the role of the active site on the activation energy?
All chemical reactions require activation energy which needs to be overcome to get them started. In chemistry you can do this by heating or by adding a catalyst. Enzymes are biological catalysts. By having the active site hold molecules in a particular orientation, this allows bonds to be made or broken easily. The activation energy is therefore lowered. With the addition of the enzyme, not as much energy is needed to allow the reaction to commence. (This is in addition to the enzyme speeding up a chemical reaction).
What is affinity?
The attraction between the active site of the enzyme and the substrate. Substrate molecules have a high affinity for the active site which allows the substrate to bind easily.The 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.
What is a competitive inhibitor?
Competitive inhibitors bind at the active site preventing the substrate from binding. Competitive inhibition can be reversed by increasing the substrate concentration.
What is a non-competitive inhibitor?
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.
What is 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.
