2.1.4 enzymes Flashcards
what is a catabolic reaction
breaks molecules down
what is an anabolic reaction
builds molecules up
what is an intracellular reaction
inside cell
e.g. hydrogen peroxide = oxygen + water, catalysed by catalase
what is an extracellular reaction
still active outside cell
e.g. digestive enzymes
starch = maltose + glucose
proteins = smaller peptides
what is activation energy
quantity of kinetic energy that reactant molecules need to collide
what do enzymes do to activation energy
reduce the amount of activation energy needed
explain the lock and key model
substrate molecule binds to complementary active site
enzyme-substrate complex formed to break bonds
products ejected
explain the induced fit model
shapes are not complementary, but substrate molecule binds to active site
enzyme changes shape to create the enzyme-substrate complex
reaction occurs, bonds break and products are ejected
what are the factors affecting enzyme activity
temperature
pH
concentration of enzyme
concentration of substrate
what is a competitive inhibitor
complementary shape to active site, blocks other substrates
what is a non-competitive inhibitor
binds to allosteric site and changes shape of active site
what is end-product inhibition
end product binds to allosteric site and temporarily changes shape of active site, only leaves when demand for product decreases so enzyme can take up first substrate again, reduces metabolic rate
what is a cofactor
a non-protein required for a protein to function
what is an inorganic cofactor
can be a permanently bound prosthetic group (haemoglobin or carbonic anhydrase) or a temporarily bound cofactor (Cl- for amylase)
what is an organic cofactor
a coenzyme (vitamins)
