1A - Enzyme action Flashcards
What are enzymes?
Globular proteins that act as catalysts lowering activation energy.
What do catalysts do?
They alter the rate of a chemical reaction without undergoing permanent changes themselves. They can be reused repeatedly and are therefore effective in small amounts.
For a chemical reaction to occur what conditions must be satisfied?
- Substrates must collide with sufficient energy to alter the arrangement of their atoms.
- The free energy of the products must be less than that of the substrates.
- Many reactions require an initial amount of energy to start. (Activation energy).
What is activation energy?
The minimum amount of energy needed to activate the reaction.
What do enzymes allow to happen in a reaction?
Allows reactions to take place at a lower temperature than normal enabling some metabolic processes to occur rapidly at the human body temperature of 37 degrees C which is relatively low in terms of reactions.
What specific region of the enzyme is functional?
The active site.
What is the active site?
The functional region of the enzyme.
What is the active site of an enzyme made of and what does it form?
It is made of a relatively small number of amino acids.
The active site forms a small depression within the much larger enzyme molecule.
What molecule does the enzyme act on?
Substrate.
When an enzyme acts on a substrate, where does it go and what does it form?
It fits neatly in the depression and forms an enzyme-substrate complex.
How is the substrate molecule held within the active site?
By bonds that temporarily form between certain amino acids of the active site and groups on the substrate molecule.
What does the induced fit model of enzyme action propose?
That the active site forms as the enzyme and substrate interact (collide).
The proximity of the substrate (a change in environment of the enzyme) leads to a change in the enzyme that forms the functional active site.
In other words, the enzyme is flexible and can mould itself around the substrate.
What happens as the enzyme changes shape?
The enzyme puts a strain on the substrate molecule which distorts a particular bond or bonds in the substrate which consequently lowers the activation needed to break the bond.
What has to happen for an enzyme to work naturally?
Reactants must collide with sufficient energy to alter the arrangement of their atoms.
The free energy of the products must be less than that of the substrates (reactants).
There must be sufficient activation energy.
What is the shape of an enzyme’s active site determined by?
The proteins tertiary structure, which in turn depends on the primary structure.
