In spite of the singular, biotechnology is in fact a combination of several technologies which draw on a number of scientific disciplines. Biotechnology as it has developed over the last 15 to 20 years is usually taken to refer to three significant technologies: 

- recombinant DNA technology 

- in vitro manipulation of cells (also called cell culture technology, or bioprocessing) 

- monoclonal antibody technology 

The European Federation of Biotechnology defined biotechnology accordingly as the 'integrated use of biochemistry, microbiology and engineering sciences in order to achieve technological (industrial) application of the capabilities of micro-organisms, cultured tissue cells, and parts thereof.'

Modern biotechnology is based on the discovery by James Watson and Francis Crick some forty years ago (1953) of the structure of DNA (deoxyribonucleic acid). Its famous double helix is made up of long and complex molecules which form two coiling strands of sugar-phosphate linked together like the steps of a spiraling staircase by four subunits. These molecular components are called nucleotides (or nucleotide bases) and contain, apart from a sugar-phosphate combination, one of four kinds of differently shaped bases: adenine (A), guanine (G), cytosine (C), thymine (T). The genetic information which determines the whole structure and the biochemical functions of the cells of any organism is encoded in the sequence, or order of these four subunits. It has been estimated that there are about three billion base pairs which are the 'steps' of the 'staircase' containing all the genetic information of a human cell.

This principle of coded information resembles that in the sequence of the letters of our alphabet, complete with stop- ('periods') and start-codes (markers for word beginnings), by which we obtain all the words of our language through the combination of just 26 letters. Similarly, the chemical substances of DNA are combined into distinct functional units—the genes—which form individual, consecutive stretches of base pairs encoding sufficient genetic information to produce simple chains of amino acids. Although the term gene preceded modern biotechnology and was first coined in 1909 to refer to Mendel's rather mysterious units of biological inheritance, its full implications emerged only when the high-tech form of biotechnology gained ascendancy. Genes vary considerably in size, and 'a typical gene might include 1,000 base pair steps in the DNA staircase and about 100 turns in the DNA double helix.' The genes represent the various words in a long text and work like commands to produce (express) all the hereditary traits in any organism. An organism's complete set of genes, comprising the totality of its genetic information, is called the organism's genome. It has been estimated that the three billion base pairs of the human genome include 50,000 to 100,000 genes. 'The rest of the genome—perhaps 95 percent of it—is nongenic sequences with unknown function, sometimes called "junk".'

The chemical components of DNA are the same in all organisms and are found in the most primitive bacterium as well as in human beings. What distinguishes one organism from the other is not the overall structure of the molecules but the different sequences of the subunits within the DNAs. 'Once isolated, any DNA molecule is the same as any other, and all can be treated with the same tools and techniques in the laboratory.'

The most dramatic implication of biotechnology lies in this fact of the sameness of DNA components and the possibility of re-arranging their order and substituting one gene for another. Although the technology for such an unprecedented manipulation of genetic information—recombinant DNA technology—began to become available only in 1973, it has 'undergone the most spectacular development' (Gendel). It quickly evolved into a powerful instrument which is now routinely used to alter the genetic make-up of a broad range of organisms, including microbes, plants and mammals.

The technology seems in principle rather simple although it requires highly sophisticated tools and clever methods to slice out a piece of genetic information of the host organism, manipulate it and transfer it to a cell of another organism. Recombinant DNA technology has developed rapidly and can now be used for a variety of purposes including the breaking down, manipulation and recombination of molecules. 'The power of recombinant DNA technology is that it permits researchers specifically to reprogram an organism to produce any desirable or useful biological product.'

The in vitro manipulation of cells is bound to revolutionize agriculture and livestock farming, and will have a strong impact on our natural environment including its fauna and flora. Although applied to the development of a variety of new bio-products both in plants and animals, the most dramatic impact of this technology lies in its capability of breaking down the species barrier by engineering transgenic plants and animals. This is based on a combination of recombinant DNA technology and cell culture technology which allows the introduction of desirable traits from various sources into the genetic make-up of an organism. 'A transgenic organism is one that carries and expresses genetic information not normally found in that species of organism.' Whereas 'traditional methods can only manipulate genetic capabilities already present within the gene pool of an individual species', modern biotechnological innovations allow creation of organisms with genetic capabilities not normally found in that particular species.'

Currently, this technique is most commonly used to improve the nutritional qualities in both plants and animals and to develop natural defense mechanisms against diseases. The application in plant production includes further strengthening of their natural properties against cold or heat, and a higher tolerance to pesticides and polluted environments.

Antibodies are extremely sensitive proteins capable of recognizing a foreign molecule from among billions of others and hooking themselves to a very specific location of it. Monoclonal antibody technology then makes use of these exceptionally important properties of antibodies to produce a variety of specific indicators of other substances to which they react. It will allow the development of numerous diagnostic testing procedures of extremely high accuracy. . .