DNA is the genetic material and is double stranded molecule made up of long chain of deoxyribonucleotides. The length of DNA is defined as number of base pairs present in it. This length of DNA is different in different organisms. In a bacteriophage known as φ 174 there are 5386 nucleotides, while Bacteriophage lambda has 48502 base pairs (bp). Bacteria like E. coli has $4.6\times {10}^6$ bp. The haploid content of human DNA is $3.3\times {10}^9$ bp.