Enzymes Flashcards
what are enzymes?
- biological catalysts with specific tertiary structures, allowing their active site to bind to specific substrates
- not used up and lower activation energy of reactions
what does the lock and key model describe
describes the substrate being perfectly complementary to the active site.
what does the lock and key model not explain
how the ES complex is stabilised
what does the induced fit model describe
it describes hoe the active site changes shape to add a strain to the substrate, reducing the activation energy of the reaction
what are extracellular enzymes
enzymes produced inside cells but secreted out of cell and act outside of cell
examples of extracellular enzymes
trypsin and amylase
what are intracellular enzymes
enzymes produced in cells that act in cells
what are catabolic reactions
large molecules broken down into smaller ones releasing energy
what are anabolic reactions
large molecules made from smaller ones using energy
what’s hydrogen peroxide
- harmful by-product of many metabolic processes
- rapidly broken down to oxygen and water by intracellular enzyme catalase
action of amylase
- catalyses hydrolysis of starch into maltose
action of trypsin
- catalyses the breakdown of peptide bonds, breaking down polypeptides into smaller ones
where is trypsin made and where does it act
- produced in pancreas
- acts in small intestine
where is amylase made and where does it act
- made in the salivary glands
- acts in the mouth
what’s enzyme activity limited by
rate of successful collisions with substrates and by shape of active site
what effect does increasing temp have on enzyme activity
- kinetic energy of the molecules increases, increasing successful collisions
- above the optimum temperature, bonds break and tertiary structure is denatured
- shape of active site changes so substrate no longer fits
what effects does change in pH away from optimum have on enzyme activity
- alters the charges of amino acids as well as the ionic and hydrogen bonds, altering the tertiary structure and denaturing the enzyme
- shape of active site changes so substrate no longer fits
what does the temp coefficient show
the increase in ror when temp increases by 10C
equation for temp coefficient
Q10 = ror at (T+10C) / ror at TC
effect of enzyme concentration of enzyme activity
- as conc of enzyme increases so does the rate as its more likely that a substrate molecule collides successfully with with active site and form ESC
- ror increases until substrate conc becomes the limiting factor so adding more enzyme has no effect
effect of substrate concentration of enzyme activity
- as substrate conc rises form 0, ESC form faster and rate increases as more substrate means that successful collision between enzyme and substrate is more likely
- eventually, all active sites will be saturated and rate plateaus as all active sites are are full
- rate will decrease over time if no more substrate is added
what are enzyme inhibitors
molecules that affect the way substrate and enzymes interact and affect product turnover
what are competitive inhibitors
- have similar shape to substrate and compete with it for the active site. Higher substrate conc will overcome this
what are non-competitive inhibitors
- bind to the allosteric site on enzymes and alter the shape of the active site, reducing maximum ror
