Expression vectors and gene transfer.

The development of DNA cloning techniques, together with the possibility of reintroducing cloned DNA fragments into the genome of a living organism, has led to an extraordinary growth of our knowledge in molecular biology over the past twenty years. In the present paper a brief overview of the vectors and techniques used in transforming different groups of organisms is given. The importance and applications of genetic engineering for each group (yeasts, plants, Drosophila and mammals) will be discussed.