unit 3 enzymes practical Flashcards
what is an enzyme
a protein molecule that acts as a catalyst in a biochemcial reaction
what are proteins made of
amino acids
what happens when an enzyme catalyses a reaction
the reaction takes place on the active site of the enzyme
what does the active site consists of
a small number of amino acids which form a specific shape because of the proteins secondary and tertiary structure.
what happens to substrates in a biochemical reaction
substrates are converted into products
what does the substrate have to the shape of the active site
has a complementary shape to the shape of the active site of the enzyme
what happens when temp goes too high
the hydrogen bonds break, enzyme changes shape, active site loses shape, so the enzyme is denatured and can no longer act as a catalyst.
what is the collision theory
in order for a reaction to occur, particles must collide and particles must have enough energy to react
what does the energy of the collision depend on
the speed of the particle and the angle they collide
what is the activation energy
the minimum energy needed for particle to react is the activation energy
how do enzymes affect the activation energy
they lower the energy, so more particles have the required energy to react, there are more successful collisions and there is a faster reaction
what does it mean when an enzyme is denatured
when the tertiary structure of the enzyme is denatured
how can enzyme reactions be measured
measuring decrease in substrate and measuring increase in product
why must the initial rate of reaction be recorded
this is because the rate will decrease as the substrate is used up and its concentration decreases
what is the optimum temp for enzymes in humans
40 degrees Celsius
how does temp affect enzyme activity
when temp increases up to the optimum, the reaction rate increases and below the temp, there is less energy so fewer collisions so slower reactions. when the temp is above the optimum, hydrogen bons break, the enzyme changes shape, the active site loses shape and the enzyme becomes denatured so no catalysis
what is the pH of most enzymes in the body
between 7-8 as this is the pH of most body cells and the blood
what is the pH of pepsin and where is it found
optimum pH is 1 and it is a stomach enzyme
how does pH affect active site
it affects the charge so if the pH changes, the charge on the active site also changes and the substrate can not bind to the active site
explain what happens when the pH of the carboxyl group of an amino acid is changed
when the pH is high, hydrogen ions are donated and it becomes negatively charged which causes the active site to may only attract substrates with a positive charge if pH environment is high
how does concentration affect enzyme activity
increases in concentration of both substrate and enzyme causes an increase in the rate of collisions which increases reaction rate
what happens when concentration of substrate is too high
there will be no more active sites for them to bind to and it will no longer affect the reaction
what happens when concentration of enzyme is too high
this means there are too many free available active sites compared to substrate molecules and so the rate of reaction will no longer increase
