By Protein is an essential constituent in all living cells. Carbon(C) Hydrogen (H), Oxygen (O) and Nitrogen (N) are always present in proteins. Sometimes Sulphur
can also be present. 17% of the mature human body is composed of proteins. Protein is a complex molecule made up of polymerized amino acid molecules. Meat, fish, egg white cereals are some of the foods rich with proteins
Significance of Proteins
- As an energy source
- When energy supply from Lipids and Carbohydrates is not sufficient protein is used in energy generation.
- To make structural components
- Proteins are important components in making cell membrane. Hairs and feathers also contain keratin protein.
- As enzymes
- All the bio-chemical reactions take place in organisms are catalyzed by enzymes. The enzymes are proteins.
- As hormones
- Some hormones are proteins which involve in homeostasis and coordination of organisms.
- As antibodies
- The antibodies that are produced in the body to protect the body against microorganisms that enter into the body are proteins.
Test to identify proteins
Biurete test
- A solution made by grinding dhal or an egg white is obtained into a test tube.
- An extra amount of Sodium hydroxide (NaOH) and then fewdrops of Copper Sulphate is added into it.(CuSO4)
- Solution turn to purple colour
Enzymes
The special proteins (organic catalysts) that are produced within the organism to increase the rate of bio-chemical reactions are known as enzymes.
For example to convert Sucrose into Glucose, Sucrose has to be heated with a dilute acid. But the enzymes present in the digestive system do the same reaction at a low temperature. Therefore the activity of enzyme is to catalyze the bio-chemical reactions. Engage in the following activity on how enzymes function.
The blue colour of the drop obtained from the mixture gradually reduces with time and finally obtains the colour of Iodine (yellow /brown colour) Starch gives black blue colour with Iodine but it does not give colour change with Iodine after 20 minutes as there is no Starch there.That is because Starch is converted to Maltose by Amylase enzyme
