miss palmer- enzymes Flashcards
what is an enzyme
type of biological catalyst which is a protien that speeds up the rate of a chemical reaction by lowering activation energy.
how do enzymes act as biological catalyst
it speeds up reaction without actually being used up in the reaction
found in living organisms that catalyse metabolic reactions
lowers activation energy
what are intracellular enzymes
works inside the cell to catalyse the reaction of hydrogen peroxide to be broken-down into oxygen and water.
if this doesn’t happen hydrogen peroxide is the toxic by-product of several cellular reactions so kills cells.
what are extracellular enzymes
works outside of cell in the human digestive system.
amylase is found in saliva so catalyses the break-down of starch into maltose in the mouth
structure of enzymes
globular proteins which have an active site determined by tertiary structure that complementary substrate binds to.
what is an induced fit
activation energy is lowered so speeds up the rate of reaction so more substrates bind making a substrate complex.
the substrate complex changes the shape slightly so this locks substrate in tightly.
how does temperature effect enzyme activity
higher temp, more kinetic energy, molecules move faster so makes substrate more likely to collide with active site until optimum temperature is reached as if temp gets to high reaction will stop as bonds break from too much vibration.
what is a temperature coefficient
the Q10 value for a reaction shows how much the rate of reaction changes when temperature it is raised by 10 degrees.
how does PH affect enzyme activity
the optimum PH is the PH at what the reaction works best.
most enzymes work best at PH7
too much above/below the H+ and OH- ions can break which disrupts the tertiary structure. this could change shape of active site so it denatures.
how does enzyme concentration effect enzyme activity
the more enzyme molecules in a solution the more likely they are to collide and form an enzyme substrate complex
however if all substrates have been used up it will have no further effect this is called the saturation point so enzyme concentration is the limiting factor
what is the saturation point
where all active sites have been used up.
what does denatured mean
active site changes shape so substrate can’t fit in.
what is a control, independent, dependant variable
control- keep same
independent- changes
dependant- measure
only one variable can be changed at once.
What is a co factor
Only works if there are another non-protein substance bound to them
What are inorganic cofactors
Help bind the enzyme and substrate
together
Not used up or changed
E.g. chloride ions are cofactors for amylase
What are organic co enzymes
Participate in the reaction and are changed by it
Carriers-move chemicals between enzymes
E.g. enzymes
What is a prostheitc group
If enzyme cofactor is tightly bound to the enzyme
E.g. zinc ions in red blood cells are permanent part of active site
What are enzyme inhibitors
They stop substrate from fitting in
What are competitive inhibitors
Similar shape to substrate do compete to fit in so no reaction takes place
Substrate concentration can increase rate of reaction up to a point
What are non -competitive inhibitors
Join to other part of enzyme away from the active site so change the shape of the active site so it’s hard to bind to
Increasing the concentration of substrate will not make any difference
What bonds are in reversible reactions
Weak hydrogen and ionic bonds
Inhibitors are reversible as they are not permanently bonded
What reaction makes inhibitors non-reversible
Strong covalent bonds that bind permanently to the enzyme
How are antiviral drugs inhibitors
Inhibits enzymes that catalyses the reciplication of viral DNA so it prevents virus from reciplicating
How are antibiotics inhibitors
Inhibits enzymes that catalyse formation of proteins in bacterial cell wall causing cell to burst and bacterium killed
