Hogness discusses what DNA is and how genetic activity is regulated in lower organisms, focusing on principles important to the use of recombinant DNAs. The most profound problem in biology is learning how gene activity is regulated in higher organisms, that is, how genes are turned on and off. The powerful tools provided by recombinant DNAs will allow scientists to isolate individual genes in pure form, yielding the solution of this problem. There are other applications of this technology, and the public‘s concerns about them are needless.