topic 1.5 - enzymes Flashcards
1
Q
what are enzymes
A
- globular proteins
- act as catalysts to speed up rate of reaction hence reducing activation energy
2
Q
lock and key model
A
- active site of an enzyme precisely fits a specific substrate
- it will not bind to any other substrate
3
Q
induced fit model
A
- this is when the shape of the enzymes active site and substrate are not exactly complementary
- when the substrate enters the active site a change of shape occurs
4
Q
stages of induced fit model
A
- substrate enters active site, forming enzyme-substrate complex
- enzyme changes shape which converts substrate into product/s, forming an enzyme-product complex
- product released from the enzymes active site
5
Q
effect of temperature on enzyme activity
A
- if temperature increases too high, enzyme will denature and stop working
- too low temps slow the reaction down
- this is why enzymes have an optimum temp at which they function best
6
Q
effect of pH on enzyme activity
A
- each enzyme has optimum pH range
- changing this pH will cause enzyme reactivity to slow down
- if pH decreases too much (becomes too acidic) enzyme denatures
7
Q
effect of enzyme concentration on enzyme activity
A
- increasing concentration will speed up the reaction as there is a substrate to bind to
- once all the substrate is bound, the reaction will not speed up
8
Q
effect of substrate concentration on enzyme activity
A
- increasing substrate concentration also increases the rate of reaction to a certain point
- once all of the enzymes have bound, any substrate increase will have no effect on the rate of reaction
- available enzymes will be saturated and working at their maximum rate
9
Q
how is the initial rate of enzyme activity measured
A
10
Q
why is measuring initial rate of enzyme activity important
A
11
Q
reversible inhibition
A
when an inhibitor affects an enzyme in a way that does not permanently damage it
12
Q
competitive inhibition
A
- competitive inhibitors compete with the substrate for the active site
- inhibitor molecule has a similar shape to the substrate molecule
- when the inhibitor binds it occupies the active site without causing a reaction
13
Q
how do competitive inhibitors work
A
- they are similar in shape to the substrate so compete to bind to the active site
- prevents substrate from binding and slows down the rate of reaction for that enzyme
14
Q
what happens to competitive inhibition when substrate concentration is increased
A
- increasing substrate concentration can reduce inhibition
- if there is a greater concentration of substrate, the substrate will outcompete the inhibitor for the active site
- so increasing the substrate concentration will increase the rate of reaction (up to a certain point, after which the inhibitor is outnumbered and has a negligible effect)
15
Q
non- competitive inhibition
A
- non competitive inhibitors do not bind at the active site
- bind to a different site on the enzyme
