Convincing evidence of common ancestry comes from the similarities in the biochemical composition, reactions and physiological activities of living beings, like metabolic process, enzymes, cytochrome $\mathrm{C}$, insulin, haemoglobin, blood and lymph etc. Genetic code is the sequence of DNA nucleotides that determines the amino acid sequence of the translated protein. The genetic code is read in triplets of bases called codons. Genetic code is applicable universally i.e. a codon specifies the same amino acid from a virus to a tree or human beings. The mRNA from chick oviduct introduced in E.coli produces an ovalbumen in the bacterium exactly similar to one formed in chick.