Enzymes

Question 1

What are enzymes

Answer 1

Enzymes are:
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)
Enzymes are specific to one particular substrate (molecule/s that get broken down or joined together in the reaction) as the enzyme is a complementary shape to the substrate
The product is made from the substrate(s) and is released

Question 1

Enzyme Action & Specificity

Answer 1

1.Enzymes and substrates randomly move about in solution

2. When an enzyme and its complementary substrate randomly collide - with the substrate fitting into the active site of the enzyme - an enzyme-substrate complex forms, and the reaction occurs.
3. A product (or products) forms from the substrate(s) which are then released from the active site. The enzyme is unchanged and will go on to catalyse further reactions.

Question 2

Enzymes & Temperature

Answer 2

Enzymes are proteins and have a specific shape, held in place by bonds
This is extremely important around the active site area as the specific shape is what ensures the substrate will fit into the active site and enable the reaction to proceed
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
Increasing the temperature from 0⁰C to the optimum increases the activity of enzymes as the more energy the molecules have the faster they move and the number of collisions with the substrate molecules increases, leading to a faster rate of reaction
This means that low temperatures do not denature enzymes, they just make them work more slowly