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Presented at the University of Liverpool, 9 December 1996 and accepted for publication on 17 February 2000.
I want to describe, in non-technical terms, what I believe the human genome project and modern genetics are. I will leave it to you to see where the ramifications of this presentation go. Because, although I will give you a few current examples, most of the returns from this new era in human genetics will be reaped in the future, not the present. Indeed, the challenge of connecting the genetics and public health agendas will only be appreciated during the 21st century.
The size of the issue
The body of a human being contains approximately 1014cells. Each one, in order for the whole to function properly, needs an appropriate repertoire of biochemical functions. Every cell has a unique history as to where it came from and how it got to be what it is; the history of a liver cell is not the same as that of a hair root cell. However, they all start with exactly the same genetic information. Every specialised biochemical function a cell performs is encoded within the same set of genes in the nucleus of that cell. Hence, genetics is important because genes determine what cells can do, and what cells can do is what organs, tissues and bodies can do!
In each nucleus there are approximately 100 000 genes. Deoxyribonucleic acid (DNA), the substance of genes, is a code in very simple molecular language. The code consists of four “letters”, “A” “T” “G” and “C”. The words of this code are three letters (or bases) long, each set of three coding for one amino acid in the resulting protein product. However, there is rather a lot of DNA; each human nucleus contains about three thousand million “letters” occupying approximately two metres of DNA (physical length unmagnified). A visual reconstruction of the DNA can be developed if you imagine …
Footnotes
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Funding: none.
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Conflicts of interest: none.