Amino acids can be defined as compounds that are made up of two functional groups namely amino group (NH2) and the carboxylic group (COOH). Amino acids are characterized by the formation of very long chains through a chemical reaction. It is through the bonding of these long chains that produces proteins. The bond so formed is known as a peptide linkage and the specific protein properties are influenced by the nature and sequence of the amino acids in it (Marchuk, 1992).
Amino acids are divided into two groups namely; essential and non-essential amino acids. Essential amino acids cannot be synthesized by the human body and must be supplied by food (Marchuk, 1992). They include isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Non-essential amino acids are those synthesized by the body from the essential amino acids or normal breakdown of proteins. They are arginine, alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, proline, serine, and tyrosine. Animal sources of proteins with the exception of gelatin contain all the essential amino acids and are therefore complete proteins. However, most plant proteins do not contain all the essential amino acids (Campbell, Mitchell, & Reece, 1999).
Deoxyribonucleic acid (DNA) is present in all cells and primarily creates encoded instructions for amino acids synthesis (Brenner, 2001). Two processes, namely; transcription and translation are involved. Transcription is characterized by the transfer of genetic information from the DNA to a similar molecule known as Ribonucleic acid (RNA). A messenger RNA contains information for synthesis of a protein. It migrates from the nucleus to the cytoplasm as it undergoes different types of maturation including splicing where the elimination of non-coding sequences is carried out.
Translation takes place in the cytoplasm. Here, the mRNA interacts with a specialized complex called a ribosome, which as a result “reads” the sequence of mRNA bases. A transfer RNA (tRNA) is responsible for assembling the protein, one amino acid at a time (Brenner, 2001). Protein assembly proceeds until when the “stop” codon is encountered.