Why is the information carrying capacity of DNA almost unlimited?
DNA is composed of pairs of four bases: adenine (A), thymine (T), cytosine (C), and guanine (G). Each base pair can be described using the following "2 bit" combinations: 00, 01, 10, and 11. A single byte or 8 bits would represent four DNA base pairs.
Therefore, the entire diploid DNA in a single cell could code for 1.5 gigabytes of information. Using an estimate of 100 trillion diploid cells in a human body, the amount of information that could be stored in the DNA of a human body would be 150 zettabytes (`~10^21` ).
As of 2011, there was an estimated 1.8 zettabytes of data in the entire world. This means that all of the data that existed in the world as of 2011 could be stored in about one teaspoon of DNA.