The genome is a manual for creating an entire organism. It’s a “full set of instructions needed to make every cell, tissue, and organ in the body,” and is written in the “four-letter language of DNA (A, C, T, and G.)”
The human genome is, at the same time, both tiny—for it can’t be seen with the naked eye—and gargantuan—for it contains three billion such “letters” or bases.
This means that if it were written out on sheets of paper, and bound into books, it’d stretch out into a tower of tomes that would be almost as tall as the Washington Monument.
If our genome is the equivalent of an encyclopedia, then all the data in it is divided into 23 “volumes,” which are present inside every cell, in the form of 23 pairs of thread-like structures called chromosomes. The chromosomes, in turn, contain genes.
Genes are the “sentences” of genetic directions that tell the cell how to make proteins, the building blocks of life. Our genome has about 20,500 such genes, but all the text within them hasn’t yet been decoded.
h/t: BROAD INSTITUTE