Question

What are $3$ best sources of protein?

Answer 1

Biomolecules are molecules that are synthesized by biological entities. Proteins, carbohydrates, lipids, and nucleic acids are some examples of biomolecules. Proteins are the most prevalent organic molecules in biological systems. Proteins are the building blocks of form and function of life.

Complete answer:
The word ‘Protein’ is derived from a Greek term ‘Proteios’ which means ‘primary’. Proteins are made up of oxygen, hydrogen, nitrogen, carbon and Sulphur. Proteins are composed of amino acids. One unit of amino acid is attached to another unit through peptide bonds. Depending on their structure’s complexity, proteins are classified into three:
Simple proteins: Proteins that when hydrolyzed give amino acids or their by-products are known as simple proteins. They are further classified into albumin, glutelin, globulin, albuminoid, protamine and histone.
Conjugated proteins: Proteins that have been combined with non-protein components are known as conjugated proteins. The non-protein part is known as a prosthetic group. Prosthetic groups can be carbohydrates, lipids, nucleic acid etc.
Derived proteins: When natural proteins are hydrolyzed, derived proteins are generated as intermediary molecules.
Proteins are found in many plants and animals. The following are some of the sources of proteins:

Animal sources: Beef, prawns, shrimps, pork, salmon, eggs, lamb, tuna etc.
Plant sources: Soybean, lentils, nuts, beans, legumes, tofu etc.

Note:
Eggs, fish and dairy products are considered as the best sources of proteins. Proteins play an important role and exhibits the following functions in our body: protein in form of enzymes are used as catalyst in biological reactions, they act as transport vehicle, they are nutrients that give strength to our body, some proteins act as storage molecule and proteins like thrombin involved in clotting of blood.