Enzymes

Question 1

what are enzymes

Answer 1

Catalysts that speed up the rate of a chemical reaction without being changed or used up in the reaction
Proteins
Biological catalysts (biological because they are made in living cells, catalysts because they speed up the rate of chemical reactions without being changed)

Question 2

enzymes and temperature

Answer 2

Enzymes work fastest at their ‘optimum temperature’ – in the human body, the optimum temperature is 37⁰C
Heating to high temperatures (beyond the optimum) will break the bonds that hold the enzyme together and it will lose its shape -this is known as denaturation
Substrates cannot fit into denatured enzymes as the shape of their active site has been lost
Denaturation is irreversible - once enzymes are denatured they cannot regain their proper shape and activity will stop

Question 3

enzyme pH

Answer 3

The optimum pH for most enzymes is 7 but some that are produced in acidic conditions, such as the stomach, have a lower optimum pH (pH 2) and some that are produced in alkaline conditions, such as the duodenum, have a higher optimum pH (pH 8 or 9)
If the pH is too high or too low, the bonds that hold the amino acid chain together to make up the protein can be destroyed
This will change the shape of the active site, so the substrate can no longer fit into it, reducing the rate of activity
Moving too far away from the optimum pH will cause the enzyme to denature and activity will stop