Metabolic pathways Flashcards
What is metabolism and what does it encompass
The chemical processes that occur within a living organism to maintain life. It encompases the integrated and controlled pathways of enzyme catalysed reactions within a cell.
Describe anabolic pathways
They are biosynthetic meaning they build up more complex molecules from simpler ones and require the input of energy.
Describe catabolic pathways
They breakdown complex molecules into simpler ones and release energy.
What are metabolic pathways controlled by
The presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes.
What is induced fit
When an enzyme changes the shape of the active site to better fit the substrate after it has binded.
Refer to the affinities of substrate and products
The substrate(s) have a high affinity for the enzymes active site while the subsequent product(s) have a low affinity, thus allowing them to leave the active site.
What is enzyme activity controlled by
temperature, pH and concentration of substrate
Explain how concentration of substrate affects the enzyme activity/reaction rate
At low concentrations of substrate the reaction rate is low as there is an insufficient amount of molecules to fill all the enzymes active sites. An increase to this concentration will increase the rate of reaction as more active sites become involved. Eventually, the rate of reaction will level off as the enzyme itself becomes the limiting factor due to having all active sites filled.
Describe the actions of competitive inhibitors
They bind to the active site of an enzyme, blocking it and preventing the substrate from binding.
Describe the actions of non-competitive inhibitors
They bind away from the active site at the allosteric site. Here they permanently alter the shape of the active site in order to prevent the substrate from binding.
What is feedback inhibition
When the end-product of a metabolic pathway reaches a critical condition, it will inhibit an earlier enzyme to prevent further synthesis of the product.
What does increasing substrate concentration do in regards to inhibition
Can reverse the effects of competitive inhibitors but not that of non-competitive inhibitors
Explain regulatory molecules within enzyme action
Regulatory molecules can bind to allosteric sites and change the shape of an enzyme to permanently hold its active site in active form.
