Enzymes

Question 1

What are enzymes?

Answer 1

Enzymes are protein molecules (made by living cells) that function as biological catalysts (speed up chemical reactions but remain unchanged at the end).

Question 2

Why are enzymes needed in cells?

Answer 2

as otherwise reactions would be too slow to sustain life.

Question 3

How does an enzyme catalyse a reaction?

Answer 3

Each enzyme has an active site where the substrate binds to the enzyme; the active site has a very specific shape, tailored to the specific substrate that the enzyme reacts on. After the reaction, you get products from the substrate.

Question 4

Why, as the temperature increases from 0°C to 38°C, does the rate of reaction become faster?

Answer 4

because the enzyme and substrate particles have increasing amounts of kinetic energy, and therefore move around faster, and are more likely to collide and react with one another

Question 5

Why does the rate of reaction briskly lower past 38°C?

Answer 5

because the shape of the enzyme’s active site is being permanently changed by the high temperature. When this happens, we say that the enzyme is denatured – this means that the substrate will no longer fit into the enzyme’s active site, so the enzyme stops working