Proteins are biochemical compounds consisting of one or more polypeptides typically
folded into a globular or fibrous form, facilitating a biological function. A polypeptide
is a single linear polymer chain of amino acids bonded together by peptide bonds
between the carboxyl and amino groups of adjacent amino acid residues. The sequence
of amino acids in a protein is defined by the sequence of a gene, which is encoded
in the genetic code. In general, the genetic code specifies 20 standard amino acids;
however, in certain organisms the genetic code can include selenocysteine - and
in certain archaea - pyrrolysine. Shortly after or even during synthesis, the residues
in a protein are often chemically modified by posttranslational modification, which
alters the physical and chemical properties, folding, stability, activity, and ultimately,
the function of the proteins. Sometimes proteins have non-peptide groups attached,
which can be called prosthetic groups or cofactors. Proteins can also work together
to achieve a particular function, and they often associate to form stable protein
complexes.
Functions of Protein for Human Body
Protein has a range of essential functions in the body, including the following:
- Required for building and repair of body tissues (including muscle)
- Enzymes, hormones, and many immune molecules are proteins
- Essential body processes such as water balancing, nutrient transport, and muscle
contractions require protein to function
- Protein is a source of energy
- Protein helps keep skin, hair, and nails healthy
- Protein, like most other essential nutrients, is absolutely crucial for overall
good health
- Antibodies defend the body from germs
- Contractile proteins are responsible for movement
- Enzymes speed up chemical reactions
- Storage proteins store amino acids