2.1.4 Enzymes Flashcards
what is an example of an intracellular enzyme?
- catalase
- works inside cell
- catalyses breakdown of hydrogen peroxide
what’s an example of an extracellular enzyme?
- amylase
- works outside cells in digestive system
- catalyses hydrolysis of starch into maltose
what do enzymes do to activation energy?
reduce it
what is activation energy?
certain amount of energy needed for a reaction to occur
how do enzymes lower activation energy?
- formation of an enzyme substrate complex
- if two substrate molecules need to join, attaching to enzyme holds them together reducing repulsion
- if enzyme is catalysing breakdown reaction, fitting into active site creates a strain in substrate bonds. bonds break up more easily
what does the induced fit model say about enzymes?
as substrate binds, active site changes shape slightly to fit substrate more easily
what factors affect enzyme activity?
- temp
- ph
- substrate conc
- enzyme conc
how does temp affect enzyme activity?
- more kinetic energy so substrates move faster and more collisions so more enzyme substrate complex formed
- if temp goes above certain level, vibration breaks bonds in enzyme, active site changes shape and substrate no longer fits
what is the temperature coefficient (Q10)?
how much the rate of reaction changes when temp is raised by 10°C
how does ph affect enzyme activity?
- too low or too high ph messes up hydrogen and ionic bonds in tertiary structure
- done by H+ and OH- ions
how does enzyme concentration affect enzyme activity?
- more enzyme molecules = more likely for a substrate to collide and bind to form an enzyme substrate complex
- ** if more enzyme than substrates**, all substrates will be used up so increasing conc will then have no effect
how does substrate concentration affect enzyme activity?
- higher chance of collision and enzyme substrate complexes forming
- more active sites used up
- after saturation point, all active sites full so increase conc will not increase rate of reaction
why is there a need for diff enzymes in diff parts of any process in the body?
- enzymes are specific
- the substrates are different shapes
- active site and substrates are complimentary
- forms an enzyme substrate complex
what is a metabolic pathway?
- series of connected metabolic reactions
- product of first reaction takes part in second reaction but each reaction is catalysed by a different enzyme
what is product inhibition?
when an enzyme is inhibited by the product of the same reaction they catalyse
what is end product inhibition?
when the final product in a metabolic pathway inhibits an enzyme earlier on in the pathway
what’s end product inhibition an example of?
- negative feedback
- high level of end product will inhibit enzyme catalysing reaction
why is environment being too acidic bad for enzymes?
- very high conc of H+ ions
- alters tertiary structure
- H+ ions affect interactions between amino acids’ R groups
- R groups no longer interact and H/ionic bonds break
how can cofactors/coenzymes affect structure of enzyme?
- change tertiary structure
- alter active site
- alter bonds in tertiary structure
what are reversible inhibitors?
weak hydrogen/ionic bonds between enzyme and inhibitor, inhibitor can be removed easily
what are irreversible inhibitors?
strong bonds between enzyme and inhibitor so inhibitor can’t be removed easily
how can the body make new enzymes when it’s denatured?
- enzymes are proteins
- transcription occurs
- translation occurs
what’s a cofactor for amylase?
Cl-
