What is the number of base pairs present in the DNA of following organisms?
i) E. coli

ii) bacteriophage lambda.

i)4.6*10⁶

ii) 48502

The length of DNA is usually represented in terms of the number of nucleotides (or a pair of nucleotides referred to as base pairs) present in it. The structure of DNA is such that between two consecutive base pairs, a distance of 0.34 nm (0.34×10⁻⁹ m) is present. Thus, one can find the total length of a DNA of an organism by multiplying the total number of base pairs with a distance between two consecutive base pairs. Since we are given the length of the DNA of E. coli as 1.36 mm, we can divide this value by the distance between two consecutive base pairs to get the total number of base pairs present. Total number of base pairs= 1.36mm/0.34x10⁻⁶mm Total number of base pairs= 4x10⁶ base pairs. E.coli has 4.6*10⁶ base pairs while bacteriophage lambda has 48502 base pairs.