Genes: Mystery Endures Despite Medical Advances

Every human cell contains more than 50,000 genes that control birth, development, health, disease and, finally, death.

The genes are packaged into 46 segments called chromosomes--23 contributed by each parent. The chromosomes, located in each cell’s nucleus, contain the molecule deoxyribonucleic acid, or DNA, the basic hereditary unit.

A gene is the portion of the DNA molecule that carries information coding for a specific protein. Proteins function as building blocks of cells and enzymes that manufacture all the molecules in the cells.

In gene therapy, a normal gene (isolated in a laboratory through recombinant DNA techniques) is inserted into the cells of a patient whose abnormal genes have caused a disease.

It is one of the enduring mysteries of life why cells “differentiate”--that is, why and how genes cause some cells to become part of a kidney and others part of an ear.