DNA or Deoxyribose Nucleic acid is made up of a ribose sugar, phosphate group and a nitrogen base(four base pairs, namely ATGC), called together a nucleotide.
The length of DNA is measured in terms of base pairs or bp.
The haploid human genome consists of 3.2 billion bases containing 20,000–25,000 protein-coding genes.
The total number of base pairs of DNA is assumed to be about 5.0×1037, weighing 50 billion tonnes.