Biotechnology and Bioinformatics (1+1)

1.2.1. DNA as genetic material

• The structure of DNA encodes all the information needed by every cell to function and thrive.
• DNA carries hereditary information in a form that can be copied and passed intact from gene ration to generation.
• A gene is a segment of DNA.
• The biochemical instructions found within most genes, known as the genetic code , specify the chemical structure of a particular protein .
• The DNA structure of a gene determines the arrangement of amino acids in a protein, ultimately determining the type and function of the protein manufactured.

The studies that have revealed the chemistry of genes began in Germany in 1869 when Friedrich Miescher isolated nuclei from pus cells (white blood cells) in waste surgical bandages. He found that these nuclei contained a novel phosphorus bearing substance that he named nuclein. Nuclein is mostly chromatin, a complex of deoxyribonucleic acid (DNA) and chromosomal protein (Chromatin = DNA +Protein).

By the end of the nineteenth century both DNA and ribonucleic acid (RNA) had been separated from the protein.

By the beginning of 1930s, P. Levene, W. Jacobs, and others had demonstrated that RNA is composed of a sugar (ribose) plus four nitrogenous bases, and that DNA contains a different sugar (deoxyribose) plus four bases. They discovered that each base is coupled with a sugar-phosphate to form a nucleotide .