Proteins are polypeptides, which are made up of many amino acids linked together as a linear chain. The structure of amino acids contains an amino group, a carboxyl group, and an R group which is usually carbon based and gives the amino acid its specific properties. These properties determine the interactions between atoms molecules, which are: ven der Waals force between temporary dipoles, ionic interactions between charged groups, and attractions between polar groups.
Proteins form the very basis of life. They regulate a variety of activities in all known organisms, from replication of the genetic code transporting oxygen, and are generally responsible for regulating the cellular machinery and determining the phenotype of an organism. Proteins accomplish their task in the body by three-dimensional tertiary and quaternary interactions between various substrates. The functional properties depend upon the proteins three-dimensional structure. The (3D) structures arise because particular sequences of amino acids in a polypeptide chain fold to generate, from linear chains, compact domains with specific structures.
The folded domains either serve as modules for larger assemblies or they provide specific catalytic or binding sites.
The cell's ability to synthesize protein is, in essence, the expression of its genetic makeup. Protein synthesis is a sequence of chemical reactions that occur in four distinct stages, i.e., activation of the amino acid that ultimately will be joined together by peptide bonds; initiation