2.1.4 enzymes Flashcards
what is an anabolic reaction?
reactions required for growth
what is a catabolic reaction?
reaction required for breaking things down
what is Vmax?
the certain point enzymes can increase the rate of reaction up to
what is the specificity of an enzyme?
the one biochemical reaction enzymes catalyse for
what is the lock and key hypothesis?
the active site fits the substrate forming an enzyme-substrate complex
when the substrate reacts and the products are formed an enzyme-product complex is formed
the products are then released
the R-groups in the active site will form temporary bonds with the substrate which put a strain on the bonds within the substrate helping the reaction along
what is the induced-fit hypothesis?
the enzyme changes shape as the substrate enters
the weak interactions between the two induces changes in the enzyme’s tertiary structure that strengthens binding and puts a strain on the substrate molecule
this weakens bonds in the substrate lowering the activation energy for the reaction
what are intracellular enzymes?
enzymes that act within cells
what does catalase do?
ensures hydrogen peroxide which is toxic is broken down into oxygen and water quickly stopping it from building up
where is catalase found?
both plant and animal tissue
what are extracellular enzymes?
enzymes that are released from cells to break down large nutrient molecules into smaller molecules in digestion
what is an extracellular enzyme involved in digestion?
amylase
what does increasing the temperature do to an enzyme?
increases KE of particles
particles move faster and collide more frequently
more successful collisions between substrate and enzyme so increase in rate of reaction
what is the temperature coefficient Q10?
measure of how much the rate of a reaction increases with a 10 degree rise in temperature
what happens to an enzyme when it denatures?
bonds holding the protein together break resulting in a change of shape in the tertiary structure of the protein causing the enzyme and the active site of the enzyme to change shape so it is no longer complementary to the substrate
what does change in pH do to an enzyme?
ionic and hydrogen bonds are affected causing a change in the tertiary shape of the enzyme meaning the active site will change shape so the substrate will no longer by complementary to the active site
what happens when the concentration of substrate increases?
increased number of substrate particles in a given volume so higher collision rate and more enzyme-substrate complexes at first therefore rate of reaction increases
what happens when the concentration of enzymes increases?
formation of enzyme-substrate complexes at a faster rate
rate of reaction increases up to Vmax but all the active sites become occupied so no more enzyme-substrate complexes can be formed until products are released from active sites
how does competitive inhibition work?
molecule as similar shape to substrate so fits active site
blocks substrate from entering
most only bind temporarily so effect is reversible
how does a competitive inhibitor affect the rate of reaction?
reduces rate of reaction but doesn’t change the Vmax
how does non-competitive inhibition work?
inhibitor binds to the enzyme at the allosteric site
causes the tertiary structure to change so active site changes shape
active site is no longer complementary to the substrate
how does a non-competitive inhibitor affect the rate of reaction?
increasing concentration of inhibitor will decrease the rate of reaction as more active sites become unavailable
what is end-product inhibition?
enzyme inhibition that occurs when the product of a reaction acts as an inhibitor to the enzyme it produces
this is negative feedback
what is a cofactor?
a non-protein helper component that that helps the enzyme carry out its function
what is a coenzyme?
an organic molecule that acts as a cofactor
where are inorganic cofactors obtained from?
diet such as minerals
what does amylase contain?
a chloride ion that is necessary for the formation of a correctly shaped active site
where are many coenzymes derived from?
vitamins
what are prosthetic groups?
cofactors that are required by certain enzymes to carry out their catalytic function
what are the differences between a cofactor and prosthetic groups?
prosthetic groups are tightly bound and form a permanent feature of the protein
