enzymes Flashcards
what are catalysts
a substance which can alter or speed up a chemical reaction, without itself being chemically changed at the end of the reaction
what are enzymes
proteins that function as biological catalysts. they can alter or speed up chemical relations. they remain chemically unchanged at the end of the reaction
what are the characteristics of enzymes
(4 characteristics)
- they speed up chemical reactions
- they are required in minute amounts
- they are highly specific in action
- they are affected by temperature and pH
why can enzymes be required in minute amounts?
they remain unchanged in the reactions they catalyse, and thus the same enzyme molecule can be used over and over again, and a small amount of enzymes are able to catalyse a large number of chemical reactions
why are enzymes highly specific in action
due to its three dimensional shape (3D shape) of the active site which is complimentary to the shape of its specific substrate
this can be explained with the lock and key hypothesis
explain the lock and key hypothesis
the enzyme is the lock, the substrate is the key
an enzyme has a specific 3D shape with a specific active site
only the substrate with a 3D shape complimentary to the active site can bind to the enzyme
this forms an enzyme-substrate complex
the enzyme catalyses reaction and products leave the active site
enzyme remains chemically unchanged and is free to combine with other substrate molecules
what is denaturation?
the process in which proteins lose their specific 3-dimensional structure and shape due to high temperature, extreme low or high pH
describe the effect of low temperature on an enzyme
at low temperature, enzymes are less active. there is low kinetic energy of enzymes and substrates, therefore there is low frequency of effective collisions and low frequency of the formation of the enzyme-substrate complex
describe the effect of the temperature rising towards optimum temperature on an enzyme
as the temperature rises, enzyme energy increases due to the increase in kinetic energy of enzymes and substrates, leading to the increase in frequency of effective collisions, and the formation of an enzyme-substrate complex
describe the effect of optimum temperature on a enzyme
at optimum temperature, enzyme activity is the highest, as there is a higher frequency of effective collisions, and therefore highest rate of formation of enzyme-substrate complex
describe the effect of the temperature going beyond the enzyme’s optimum temperature
beyond optimum temperature, enzyme activity decreases ad the high temperature denatures the enzyme, and so its specific 3d shape and active site is altered, and the enzymes are unable to bind with the substrate, resulting in the decrease in frequency of effective collisions and rate of formation of the enzyme-substrate complex
describe the effect of optimum pH on enzyme
at optimum pH, enzyme activity is the highest, as it’s specific 3D shape and active site is intact, so it is able to bind to the substrate with its complimentary shape. this results in the highest rate of formation of enzyme-substrate complpex
describe the effect of optimum pH on enzyme
at optimum pH, enzyme activity is the highest, as it’s specific 3D shape and active site is intact, so it is able to bind to the substrate with its complimentary shape. this results in the highest rate of formation of enzyme-substrate complex
describe the effect of extreme change in pH
when there is extreme changes to the pH, enzyme activity decreases as the enzymes get denatured and lose the specific 3D shape and active site, making the enzymes unable to bind with the complimentary shape. this decreases the rate of formation of the enzyme-substrate complex
