Enzymes Flashcards
what is an enzyme?
an enzyme is a protein that functions as a biological catalyst. they speed up reactions without being altered in the process.
what are enzymes made of?
enzymes are protein in nature - this means they are made of amino acids; they are usually made up of a few hundred amino acids linked together
shape of an enzyme
enzymes have very definite 3D shapes. anything that alters the shape of the enzyme will affect the rate at which the enzyme works
what is the active site?
every enzyme has a region on it‘s surface are called the active site. this is the part of the enzyme to which the substrate binds.
the active site has a very definite shape and only a substrate with the complementary shape can fit into the active site.
each enzyme only works with _____ _______, so it can only _______ one type of ________
one substrate, catalyse, reaction
how do enzymes speed up reactions
enzymes speed up reactions by binding to a substance called a substrate and lowering the energy needed to change the substrate into a product
mechanism of enzyme actions
C B C E P R U
- enzyme and substrate must collide in such a way that the substrate binds to the active site of the enzyme
- an enzyme substrate complex is formed
- energy level is lowered by the enzyme so that the substrate is changed into a product
- product is released and the enzyme is unchanged to it can repeat the whole process
what is the effect of low temperatures on enzyme action?
at low temperature the rate of enzyme action is low due to the fact that the molecules of enzyme and substrate have very little kinetic energy. therefore, the rate of successful collisions is lower.
enzymes are NOT denatured at low temperatures, they just lose kinetic energy.
what happens as the temperature increases?
the kinetic energy of the molecules of enzyme and substrate increases, thus there is a higher frequency of effectice collisions between enzyme and substrate molecules, so the rate of reaction increases
what happens when the temperature goes above 37? (above optimum temperature?)
enzyme denaturation begins. this causes the shape of the enzyme‘s active site to change so that the substrate can no longer fit into the active site, it cannot bind with the enzyme properly.
the denaturation gets progressively worse as the temperature increases. the shape of all active sites is destroyed by 60• celsius
deacribe the effect of temperature on the rate of enzyme action
- low temperature: rate of enzyme action is low
- as the temperature increases from 0 to 37, the rate of enzyme action increases
- the maximum rate is reached at 37, so this is the optimum temperature for the enzyme
- as the temperature increases above 37, enzyme action decreases rapidly until there is no action at all at 60
every enzyme has a particular ____ at which it works best. this is called the _____ __.
pH, optimum pH
what happens wen the ph affects an wnzyme?
if it is too high or liw, the pH interferes with the bonds holding they enzyme together. this denatures the enzyme.
