All living organisms are composed of proteins, which are chains of specific groups of amino acids linked together by chemical bonds. Protein synthesis begins in the cells where proteins carry out all the biological processes that sustain life. Amino acids, also called the building blocks of protein, fall into three categories: essential amino acids, which the body cannot make, and nonessential and conditional amino acids, which the body can synthesize. According to the University of Arizona, protein production is so vital to survival, if a sufficient amount of just one essential amino acid is not obtained from food; the body takes that amino acid from muscle tissue and other sources of protein within the body.
Thirteen years after the human genome was sequenced, two research groups have independently mapped the extent to which cells in various organs in the body turn many thousands of genes into proteins. From bacteria to humans, genes are made up of units of DNA; called base pairs in genes tell a cells molecular machinery what proteins to produce. Ultimately, it is the proteins that carry out a myriad processes essential for life.
Once the over three billion base pairs the make up the human genome were sequenced, analysis of that date indicated that there are about 20,000 protein-coding genes. Proteins produced by normal cells in 30 tissue samples, adult and foetal as well as those found in blood. House keeping proteins from 2,350 genes that were produced in all tissues. On the other hand, proteins from 1,537 genes turned up in only one of the tissues. A number of proteins were expressed only during foetal development. Organ specific proteins could be used for detection of diseases arising in those organs.
Proteins from about 84 per cent of all human genes, the remaining genes may have eluded detection. Proteins expressed in tissues or organs that not been sampled. Alternatively, they might be expressed at very low levels, requiring special techniques to track down. Proteins found in various human tissues, cell lines and body fluids. Hundreds of genes described in the human genome apparently do not code for protein any more. A family of proteins involving some 800 genes that is important for sensing smell and taste. But proteins could not be found from more than half of those genes.
Blood contains a constant supply of amino acid chemicals to fulfill the bodys continuous need for protein. Instructions for making protein molecules are encoded in the DNA of genes. Explained simply, protein production occurs in a cell when DNA molecules transfer the genetic code for assembling amino acids to other molecules RNA and ribosomes. Specific amino acids are arranged in proper sequence to build each protein molecule according to the function it will serve.