75. What are enzymes?
To keep us alive, various processes keep on going in our body. These
are largely chemical reactions.
To speed up these reactions, the body cells produce catalysts which
are known as enzymes. A single cell may contain 100,000 different
enzymes, which are needed to take part in its 1000 to 2000 chemical
reactions.
Some enzymes link simple substances together to form the more
complex ones needed to build up tissues. Some digestive enzymes
convert food into simple substances. The enzymes are made of
protein and each enzyme has a different shape. It has an active site
known as the lock. It is shaped so that only a molecule of the correct
shape and size known as the key, can produce a chemical reaction.
After the reaction, the product separates from the enzyme, leaving as
it is A particular type of enzyme can take part in only a particular
reaction. Enzymes work best at a particular temperature, hence we
have constant body temperature. Some digestive enzymes are:
(i) Amylase: Present in saliva and pancreatic juice. It converts starch
to sugar.
(ii) Maltose: Present in saliva and small intestine. Converts starch to
sugar.
(iii) Pepsin: Produced in the stomach. Breaks down protein.
(iv) Renin: Present in the stomach. It helps to digest milk.
(v) Trypsin: Produced by the pancreas, it breaks down proteins.
