6. Enzymes Flashcards
What are enzymes?
Proteins that speed up the rate of chemical reactions.
How do enzymes speed up chemical reactions?
Acting as a biological catalyst.
What is the active site of an enzyme?
The active site has a specific shape.
Its part of the enzyme where the substrate molecule binds to.
How are enzymes highly specific?
Due to their tertiary structure.
Enzymes can catalyse what type of reactions?
Metabolic reactions at both cellular level (respiration) and for the organism as a whole (digestion in mammals).
Give an example of how enzymes can affect structures in an organism?
Enzymes are involved in the production of collagen, a important protein in the connective tissues of animals.
As well as functions (respiration).
What can enzyme action either be?
Intracellular - within the cells.
Extracellular - outside of cells.
What is the activation energy?
The certain amount of energy needed to be supplied to the chemical before the chemical reaction starts.
Often provided as heat.
What do enzymes do to the activation energy?
They lower the amount of activation energy needed.
Making reactions happen at lower temperatures then they could without an enzyme.
This speeds up rate of reaction.
What is a catalyst?
A substance that speeds up a chemical reaction without being used up in the reaction itself.
What happens when a substrate fits into an enzymes active site?
It forms an enzyme-activation complex - lower activation energy.
Why does an enzyme substrate complex lower the activation energy?
If 2 substrate molecules need to e joined, being attached to the enzyme holds them close together, reducing an repulsion between the molecules, bond more easily.
-If the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate , substrate molecule breaks up more easily.
What is the lock and key model?
Where the substrate fits into the enzyme in the same way that a key fits into a lock.
The active site and the substrate have a complementary shape.
What did scientists soon realise about the lock and key model?
The enzyme and subsrate do have to fit together in the first place but new evidence showed that the enzyme -subsrate complex changed shape slightly to complete the fit.
What is the induced fit model?
Its shows us that the substrate doesn’t only have to be the right shape to fit into the active shite, it has to make the active site change shape in the right way as well.
