Unit 2 key area 1 Flashcards
Describe what is meant by the term “metabolic pathways”?
Metabolic pathways are integrated and controlled pathways of enzyme controlled reactions within a cell.
What are some of the typical features of a metabolic pathway?
Metabolic pathways involve reversible steps, irreversible steps, and alternative routes.
What are the different types of reactions within a metabolic pathway?
- Catabolic reactions
- Anabolic reactions
Describe an anabolic reaction?
In an anabolic reaction large molecules are built up from smaller more simple molecules and require energy
Describe a catabolic reaction?
In a catabolic reaction smaller products are produced from a larger molecule and release energy.
What types of molecules are embedded in membranes?
protein pores, pumps and enzymes
Describe how metabolic pathways are controlled?
metabolic pathways are controlled by the presence or absence of particular enzymes, and “regulation” of the rate of reaction of key enzymes.
Describe what is meant by the “induced fit model”?
In the induced fit model when a substrate binds to the active site of its specific enzyme the enzyme will change its shape slightly to better fit the substrate.
What can the word “affinity” be used to describe in terms of the induced fit model?
- The substrates have a high “affinity” for the active site of their specific enzyme
- The products have a low “affinity” for the active site of their specific enzyme and so they detach from it
Describe how competitive inhibitors act in a metabolic pathway?
Competitive inhibitors bind at the active site preventing the substrate from binding to the enzyme to form the enzyme substrate complex. This process can be reversed by increasing the concentration of the substrate.
Describe how non-competitive inhibitors act in a metabolic pathway?
Non-competitive inhibitors bind away from the active site to the allosteric site, this causes the shape of the active site to change and preventing the substrate from binding to it. Non-competitive inhibition cannot be reversed by increasing substrate concentration.
Describe the process of feedback inhibition?
Feedback inhibition occurs in a metabolic pathway when a substance reaches a critical concentration. The end product will then inhibit an earlier enzyme preventing further synthesis of the end product.
