Biological Molecules - Enzymes Flashcards
What are the conditions required for enzyme reactions?
The molecules need to collide with enough energy to alter the molecular arrangement
The substrates must have the minimum amount of energy (activation energy)
How do enzymes alter their conditions in order to break down substrates?
they put strain on the active site which lowers activation energy, allowing reactions to take place at lower temperatures eg 37 degrees
Why do enzymes denature above 37 degrees?
The hydrogen bonds between the NH and OH groups are broken, causing the enzyme to change shape - denaturing the enzyme
Describe the induced fit model of enzymes
The active site of the enzyme only takes the shape of the substrate when they collide
flexibility in polypeptide chains allows enzyme to shape its active site around substrate - if all the bonds are formed in the right places T
now used in the place of the lock and key theory
Describe the lock and key model for enzymes
The enzyme is constantly shaped to fit the substrate - it never changes shape
This is inaccurate and no longer used
What are the factors affecting enzyme activity?
Temperature
pH
enzyme concentration
substrate concentration
How does the temperature affect enzyme activity?
Increases enzyme activity up to 37 degrees
After 37 degrees the enzymes begin to denature H+ bonds to holding together the tertiary structure breaks active site deforms
Below - not enough E to react
How does pH affect enzyme activity?
If the pH is above OR below optimum pH, the H+ and OH- bonds interfere with the ionic and H bonds in tertiary structure, deforming the active site and denaturing the enzyme
What is the optimum pH for enzymes?
Most in humans is around pH 7
However pepsin (digests proteins in the stomach) has an optimum pH of 2
What are the 2 types of enzyme inhibition?
Competitive and non-competitive
What is competitive inhibition?
When a molecule other than the enzyme’s specific substrate is complementary to the active site of the enzyme, occupying the enzyme and slowing down the rate of reaction
What is non-competitive inhibition?
When a molecule attaches itself to the enzyme (not the active site) and distort the enzyme shape, denaturing it
