Metabolic pathways Flashcards
What are metabolic pathways?
a series of enzyme catalysed reactions and the steps are connected by their intermediates
What is cell metabolism
the collective term for the biochemical reactions thay occur in a living cell
What is an anabolic pathway?
build up of large molecules from smaller molecules and requires energy
What are catabolic pathways
break down large molecules into smaller molecules and release energy
What are metabolic pathways controlled by
the presence or absence of particular enzymes in the metabolic pathway
the regulation of the rate of reaction of key enzymes
Describe induced fit
the substrate attaches to the active site on the enzyme
the substrate molecule have a high affinity for the active site
the active site orientates the substrate
this causes an induced fir where the active site changes shape to better fit the substrate after the substrate binds
this lowers the activation energy
products are released as they have a low affinity to the active site
What is induced fit?
the active site changes shape to better fit the substrate after the substarte binds
How is rate of recation affected by substrate concentration
when substrate concentration is low all the active sites on the enzymes will not be occupied so rate of reaction is slow.
increasing substrate concentration will cause the rate of reaction to increase as more active sites will be occupied
when all the active sites are occupies increasing substrate concentration does not give rise to an increase in reaction rate
What is a competitive inhibitor?
has a similar shape to the substrate and binds to the active site
Describe competitive inhibitors?
if the substrate concentration increases the rate of reaction will increase until it reaches the maximum rate of reactin
Competitive inhibition can be reversed by increasing the substrate concentration
Describe non competitive inhibition
binds to the allosteric site on the enzyme and changes the shape of the active site which prevents the substrate molecule binding
if the substrate concentration increases the maximum rate of reaction will not be reached
non competitive inhibition cant be overcome by increasing substrate concentration
Describe feedback inhibition
occurs when the end product in the metabolic pathway reaches a critical concentration
the first enzyme can be inhibited by high levels of the final product of the pathways occurs when too much of the end product is produced
feedback inhibition beneficial because it prevents waste of energy and resources when product not needed
What is activation energy?
The energy required for a reaction to occur
Explain how a competitive inhibitor can reduce the rate of an enzyme controlled reaction
competitive inhibitors have a structure similar in shape and charge to that of an enzyme substrate. Inhibitor molecules will bind to the active site preventing the binding of a substrate
Inhibition by a non competitive inhibitor cannot be overcome by increasing the substrate concentration why not?
because the enzymes active site has changes shape
