The Units of Genetic Information

The story of the discovery of the genetic material is fascinating but complex and cannot be covered here (interested persons should consult James Watson's The Double Helix, as informative about the personalities involved in the race to apprehend DNA as the pertinent molecular biology). For many years, it was thought that proteins performed this function. By the middle of the 20th century, however, a series of elegant experiments had proved that a little-regarded biochemical called deoxyribonucleic acid was the vehicle of heredity.

Humans have over 100,000 distinct genes. They are not just all floating around loose in the cell. The highest level of genetic organization is the chromosome, a tightly coiled complex of DNA and proteins. These bodies duplicate, diverge, and recombine in the process of cellular replication.

At one point it was believed that each gene coded for a specific protein. This idea is no longer valid. Most genes probably do code for the various proteins that are essential for the proper functioning of cells and organisms, but others are transcriptionally silent and exactly what these do has not been completely worked out. Some are regulatory, providing binding sites for proteins that influence gene replication and transcription.

Bear with me--there's a point to all this.