Genetic Scientists

In the 1860s, an Austrian monk named Gregor Mendel discovered the principles of genetics by breeding different varieties of garden peas in his monastery garden. His experiments, which showed that crossing short and tall peas produced only tall plants rather than any of medium height, proved that no blending of traits occurred. Rather, tallness was the dominant (or more powerful) trait and shortness was recessive.

Fifty years after Mendel's discoveries, American biologist Thomas Hunt Morgan discovered that genes are located on the chromosomes present in every cell. Genes are like a blueprint: They carry instructions for how an organism—human, animal, or plant—will be built. However, as Hugo de Vries discovered in his research in the early 1900s, genes do not always copy themselves exactly. Sometimes they mutate, that is, change their blueprint from one generation to the next. Mutations are often responsible for illness.

The modern history of genetics began in the early 1950s with James Watson's and Francis Crick's discovery of the double helix, or spiral ladder, structure of DNA. Their discovery touched off a flurry of scientific activity that led to a better understanding of DNA chemistry and the genetic code. Before 1975, however, the technology for actually altering the genes of organisms for study or practical use was severely limited. For while the 1950s and 1960s saw big successes in gene transfer and molecular biology for the smaller and simpler bacteria cells, more complex organisms were another story. Even though both plant and animal cells could be grown in culture, the detailed workings of their genes remained a mystery until the discovery of recombinant DNA techniques. Recombinant DNA refers to combining the DNA, or genetic material, from two separate organisms to form unique DNA molecules that carry a new combination of genes. The major tools of this technology—and the second most important discovery in the field of genetics—are restriction enzymes, first discovered in the 1960s. They work by cutting up DNA molecules at particular points so that DNA pieces from different sources may be joined. These genetically engineered cells may then be cloned, or grown in culture, to make copies of the desired gene. The cloning of genetically engineered cells has many potentially useful applications for society, such as producing pest-resistant plants, altering bacteria for waste cleanup, or generating proteins for medical uses like dissolving blood clots or making human growth hormone.

The most ambitious project in DNA research to date made possible by advanced technology was the effort to map the entire human genome, or all the genetic material in human beings. Called the Human Genome Project (HGP), it is considered more important to science history than either the splitting of the atom or the moon landing. The U.S. government launched the HGP in 1990, with the goal of completing the sequencing by 2005. In 1998, Celera Genomics Corporation (a for-profit company) announced that it would start its own sequencing project to compete with the HGP. By 2000, both organizations had completed rough drafts of the human genome. Project results promise new scientific knowledge, medicines, and therapies that can be used to battle diseases such as AIDS, cancer, arthritis, and osteoporosis. Continuing advances in automation and electronics, including use of the latest data analytics software, will greatly promote project goals and increase our understanding of genetics.