The present material is published on the initiative of a complex creative youth team (CYC) and is written mainly by its members. The need to write such material is associated with the very rapid development of methods of molecular genetics and genetic engineering and their introduction into many branches of biological science. Only a few years ago, these methods were the property of only two laboratories of our Institute, and now they are mastered or already actively used in ten major laboratories or groups. Molecular-genetic methods are quite time-consuming and, in order to master them, as a rule, considerable effort and time are required. At the same time, we are experiencing an acute shortage of methodological literature on genetic engineering, and even the recent publication in Russian of the remarkable book T.. Maniatis, E. Fritsch and J. Sambrooke's "Molecular Cloning" Hasn't Completely Solved This Problem.