In 1938 a Dutch chemist Mulder Gerald suggest ed the word proteos, that's a Greek word and it means to take first place. It's a vital substance to make protoplasm and a base matter of living cells. Protein is made of carbon, hydrogen, nitrogen and oxygen. In few proteins, there are sulfur and phosphorus also present. All living cells like blood cell, bone, soft tissues, teeth are largely made up from protein. This is found almost in every tissue except bile and urine.


Amino acids are the basic units of protein. They are made of amino acids, mainly protein has 22 amino acids which are made protein but there are 10 amino acids which are important for the development of our body and can't make by our body. They are called essential amino acids. They are 10 for adults and 8 for children. Rest amino acids are called nonessential amino acids because they generate by the body and they have no important role in body development.
Quality of protein is depending on amino acids quality and quantity. There are 2 types of amino acids.
1) Essential amino acids:
Lysine Tryptophan, leucine, valine, isoleucine, threonine, methionine, phenylalanine, arginine, histidine.
2) Nonessential amino acids:
Alanine,aspartic acid,cystine acid,glycine-serine,glutamic acid,proline.

Types of protein.

i) By  quality:
There are some kinds of protein which are classified by their quality such as complete protein. Complete protein is an essential compound of diet. They are compulsory for growth and development for the living being. There is some example of these kinds of animal protein. Ex. Casein and lactalbumin of milk. Ovalbumin and Ovovitellin in egg, Tryptophane and leucine in meat. Another kind of protein which are partially complete protein,  while they can make us alive but not play an important role in body nourishment and development due to lack of some essential amino acid such as legumine in pees, peanut and soybean protein.

Incomplete proteins are also a kind of quality protein division they have no essential amino acids. They are a kind of poor quality such as zein protein in the maze(Corn), gelatin of fruits protein of green leafy vegetables.

ii) By Occurrence of protein:
Protein is occurred in two forms in nature.
1) Vegetable protein
2) Animal Protein

Aminal proteins are A grade protein and vegetable protein are B grade protein. Eggs, Cheese, Milk, Meat, Fish, are the example of an animal protein and have a biological value. Peas, peanut, pulses, dry nuts are the examples of vegetable protein and have low biological value. Eggs have hundred percent NPU(Net protein unit) and food and agriculture organization suggested it for reference protein. Animal protein is more beneficial for development and growth than plant or vegetable proteins.

iii) By chemical activity:   They are also classified into three kinds of proteins
a) Simple protein
b) Conjugated protein
c) Derived protein

Simple protein

These proteins are produced only amino acids after hydrolysis such as albumin is water soluble and get solid after getting temperature egg albumin, legume of peas, lactoalbumin of milk are the example of this kind of protein. Globulin is insoluble in water but soluble in neutral salt solution, serum globulin of blood, ovoglobulin of eggs are the example. Protamine is water soluble and not get solid on temperature. Histone is water-insoluble but soluble in ammonia such as thymus, histone and hemoglobin. Prolamin is insoluble in water and neutral solution but soluble in concentrate alcohol. Send of the maze, glydean of wheat. Glutelin is also insoluble in neutral solution and soluble in dilute acids and bases such as Arginine of rice.

Conjugated proteins

They contain phosphorus, lipids and carbohydrates for example nucleoprotein,_ this is made of protein and nucleic acids, this kind of protein is present in the thymus gland. Glycoprotein, phosphoproteins, flavoproteins, mucoprotein, lipoproteins, chromoprotein are the examples of conjugated proteins.

Derived proteins

They are not found in this form, so they can obtain only after hydrolysis of simple or conjugated proteins. They are also in 2 kind Primary derived proteins Secondary derived proteins Amino acid is the last production of protein. Protein is completely converted into amino acid as the last production after complete hydrolysis. We Can understand this system by this path.

Protein -> Protean -> Metaprotein -> Protios -> Peptone-Peptide -> Amino acid .


It is present in both animal and plant cells animal sources such as milk, fish, meat, are the good sources of protein. Pulses nuts cereals are also good in protein but not like animal protein. Vegetable and fruits are less in protein. We can use amino acid supplementation to enrich the protein diet. Yeast and blue-green algae are also a good source of protein but excessive use is being unhealthy and caused nausea and vomiting. Mushrooms and fungi are the good sources of protein in the vegetable group, soybeans are also rich in protein from vegetable group.


They are used generally in bodybuilding function like enzyme hormones and antibodies proteins are building blocks for body and they made of amino acids. Protein does repair function of damage in cell and bones after an injury or surgery. Plasma protein of blood helps to maintain osmotic pressure to balance water in our tissues and regulates water balance in the entire body a main and important function of the protein is to regulate the balance of acid and base. Protein is amphoteric in nature it helps to maintain the alkaline ph 7.35 to 7.45 in our body which is necessary for us. Although the main function of the protein is to maintain and build up a body but protein can also provide energy, 1 gm protein gives us 4 Kcal. So in severe condition or in case of less intake of fat and carbs protein are used to give energy to our body.

Deficiency of protein:

In small children they suffer from kwashiorkor and deficiency of protein plus carbohydrates is called marasmus. In adults deficiency of protein can pause underweight, weak immunity loss of lean tissue, hair loss, gallstone, Oedema, hypotension, fatty leaver, diarrhea, vomiting, tuberculosis, anemia, muscle wasting helminthic infection.


Daily Requirement:

According to dietary reference intake (DRT) daily requirement of protein is 0.8gm per Kg of body weight (0.36gm per pound)  and its 46gm for an average sedentary woman and 56gm for an average sedentary male per day, but in growing children, pregnant and lactating women are needed more protein. we should give +15 gm extra for pregnant and +25 gm for the lactating woman in 0-6 months and +18 gm extra in 6-12 months.