In 1975, recombinant DNA sequencing methods were developed. From being the most difficult macromolecule of the cell to analyze, DNA has become the easiest. It is now possible to isolate a specific region of a genome, to produce a virtually unlimited number of copies of it, and to determine the sequence of its nucleotides overnight.

These technical breakthroughs in genetic engineering—the ability to manipulate DNA with precision in a test tube or an organism—have had a dramatic impact on all aspects of cell biology by facilitating the study of cells and their macromolecules in previously unimagined ways.

They have led to the discovery of whole new classes of genes and proteins, while revealing that many proteins have been much more highly conserved in evolution than had been suspected.