the thread of life

The projetct was completed in 2003. The goals of the project were:

• to identify all genes in human DNA
• to determine the sequences of the DNA base pairs
• to store this information in data bases, to improve tools for data analysis, to transfer related technologies to the private sector
• to adress ethical, legal and social issues

The reagent ***** has a small colured square at one end that turns a different colur in the presence of glucose. This square is impregnated with four reagents:

- glucose oxidise (enzyme - catalyst)

glucose + oxygen -> gluconic acid + hydrogen peroxide 

- indicator (sometimes 2-methylphenylamine)

- peroxidase (enzyme - catalyst)

hydrogen peroxide + XH2 (colourless) ->water + X (coloured)

- a buffer (keeps reagents at a fixed pH during the test)

- it has ribose as sugar (hence it's called ribonucleic acid)
- it has the base uracil instead of thyimine (these differ by a methyl group)
- it exists only as a single strand

It is based on the fact that no two people share the same DNA sequence ( regularly used to help investigate serious crimes).
A trace of blood, semen or skin can be used. A solution of enzyme is added (cuts the DNA into particular sites into specific pattern of fragments). Fragments of genes not used (don't vary much between individuals). The 'stop' codons however do vary.

The solution is applied to a gel; then subjected to an electrical field (gel electrophoresis).
Radioactive tracers are added (it binds to DNA fragments; a series of bands are seen that are compared with the DNA sample of the suspect).