Unit 1- Metabolic Pathways Flashcards
Describe an anabolic pathway
Simple molecules built up into complex molecules, requiring energy.
Describe a catabolic pathway.
Complex molecules broken down into simple molecules, releasing energy.
Define cell metabolism
Cell metabolism is the collective term for all the biochemical reactions that occur in a living cell.
Describe metabolic pathways.
They are pathways controlled by, the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes. They can have reversible or irreversible steps.
Describe the affect of an enzyme on activation energy.
An enzyme lowers the activation energy.
Describe induced fit
Induced fit occurs when the active site changes shape to better fit the substrate after it binds. The substrate molecules have a high affinity (attraction) for he active site. The products have a low affinity for the active site. High affinity = high attraction.
What descreases an enzymes activity
Inhibitors. Used in metabolic pathways to control enzyme activity.
What are the two types of inhibitors.
Competitive,non competitive.
Describe a competitive inhibitor.
Competitive inhibitors bind directly to the active site and prevent the substrate molecules from binding and reacting there .
Describe a Non-competitive inhibitor.
Non competitive inhibitors bind elsewhere on the enzyme molecule but permanently altar the shape of the active site. This prevents the enzyme from binding properly with the substrate.
Are competitive inhibitors reversible or irreversible? Why?
Reversible, by adding more substrate. This will mean that more and more active sites will be occupied by substrate molecules rather than inhibitor molecules and the reaction rate can increase again.
Are non competitive inhibitors reversible or irreversible? Why?
Irreversible (adding more substrate makes no difference to the rate of reaction), most enzyme molecules have become inactive but so,e are unaffected by the inhibitors, so reaction rate remains low.
Describe feedback inhibition.
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.
