2.5 + 8.1 enzymes and metabolism Flashcards
what is anabolism
synthesis of larger molecules from smaller molecules
what is catabolism
breaking down complex molecules into smaller molecules
what is metabolism
- all enzyme catalysed reactions in a cell
- includes anabolism and catabolism
what are enzymes
biological catalysts that increase the rate of reaction without being consumed
what are 3 features of enzymes?
- enzymes lower Ea of reactions
- enzymes are highly specific as its active site is complementary in shape to its substrate
- enzymatic activity is lost when denatured due to loss of 3D conformation of active site
the two models of enzyme action are…
lock and key, induced fit
what does the lock and key model propose?
- the active site is inflexible with a rigid shape
- only substrates with exact shape can fit in active site
- lock = active site on enzyme and key = substrate
how does the induced fit model extend the lock and key model?
- increases the range of substrate specificity
- proposes that when a substrate binds to an enzyme, it induces a change in conformation of the enzyme’s active site
what affects enzyme activity? (5 briefly)
- temp
- pH
- [substrate]
- [enzyme]
- [enzyme inhibitor]
how does temp affect enzyme activity?
- incr temp -> incr kinetic energy
- thus incr rate of effective collisions btw substrates and enzymes
how does pH affect enzyme activity?
- pH affects the structure of the enzyme
- drastic pH changes can cause denaturation, changing the shape of the active site
what is the effect of increasing [substrate]?
- incr substrate leads to more chances of effective collisions w enzymes -> incr the % of active sites occupied
- at high [substrate] there is saturation of all active sites
how do competitive inhibitors work?
they compete with the substrate at the active site
how do non competitive inhibitors work?
they bind to the allosteric site to alter the shape of the active site
_________ inhibition can be overcome by increasing [substrate]
competitive
what is a structural feature of competitive inhibition that enables it to function as a competitive inhibitor?
the inhibitor and substrate are similar in shape
the synthesis of isoleucine from threonine involves _________ inhibition
end product
end product inhibitors are typically _________ inhibitors
non-competitive
how does end product inhibition control metabolism?
- end product of a metabolic pathway acts as an inhibitor of the first enzyme in the pathway
- accumulation of end product incr its chances of inhibiting the enzyme to stop the metabolic pathway
what is a metabolic pathway?
a chain of enzyme-catalysed reactions
in the synthesis of isoleucine, who is the end product inhibitor?
isoleucine
what enzyme is used in the synthesis of isoleucine?
threonine deaminase
isoleucine is an [competitive/non-competitive] inhibitor
non-competitive
explain the end product inhibition of isoleucine
- isoleucine is synthesised from threonine
- isoleucine is non competitive inhibitor of threonine
- binds to allosteric site of threonine deaminase,
the enzyme in the first step - stops the metabolic pathway
what are 2 ways enzymatic reactions can be tracked?
measure
1. rate of pdt formed
2. rate of disappearance of substrate
why are enzymes immobilised (brief)
- so they can be reused
- so the reaction can be stopped quickly by removing the enzyme
what is an example of enzyme immobilisation in the industry?
lactose-free milk
who needs lactose-free milk
individuals w lactose intolerance
how is lactose-free milk produced?
regular milk with lactose is passed over immobilised lactase
