From DNA molecule to Human

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From DNA molecule to Human Share this with your friends

1. The four letters of DNA

All genetic code is spelled out with just four chemical letters, or bases:

adenine (A),
thymine (T),
cytosine (C)
and guanine (G).

These pair up, A with T and C with G. The human genome has between 2.8 and 3.5 billion base pairs.