Imagine that you are trying to solve a jigsaw puzzle. If you can put all the pieces of the puzzle together, you will understand many of the mysteries of the human body.

There's only one hitch. this puzzle has quite a few pieces. Over three billion, to be precise.

By the year 2006, microbiologists hope to master just such a puzzle--that of the human genome.

The human genome consists of all the hereditary information of human beings. This information exists in long chains of amino acids known as DNA sequences. Scientists are currently attempting to sequence the entire human genome, in the $3 billion Human Genome Project.

Already, researchers have identified a significant portion of genes on the genome. Earlier this month, scientists at the National Institutes of Health (NIH) reported that they had found one in twenty such genes.

One use of this data will be the diagnosis of disease through the genetic analysis of blood samples. Geneticists will also obtain a wealth of information about how humans function and how they have evolved.

And Harvard's science departments, from biology to virology, are playing an important role in the project's daily discoveries.

The project is a worldwide effort to analyze the structure of DNA, the chemical component of genes, and to determine the exact location of genes in humans and many other model organisms. Scientists are attempting to create a physical and genetic map of the chromosomes of the various organisms.

The last time the federal government funded a scientific undertaking of this magnitude was the Apollo project.

One aim of the project is to form a computer database containing the genetic sequences that have been discovered. This will make the information accessible over computer networks around the world.

"Genetic sequences have been emerging around the world and scientists thought that it would be useful to have an organized base of genetic knowledge," says Loeb University Professor Walter Gilbert, whose lab represents a large portion of Harvard's genome project efforts.

Gilbert says that geneticists hope to learn a great deal about the human body not only for the advancement of medicine, but also for purely scientific purposes.

Scientists are sequencing genes in order to understand the structure of the proteins they encode, he says.

Genes determine most biological phenomena and are key in learning how the body works.

"By elucidating and putting together the 100,000 genes of the human body, we can discover how the body itself functions," Gilbert says.