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Did you know that a transgenic is a new breed of organism produced without sex, in which a gene from one species is transferred - by a technician in the laboratory - and incorporated into the genome of another species, often on a far branch of the evolutionary tree? Transgenic mice, pigs, sheep, rabbits and E. coli have all been created with different human genes inserted into their genomes. Did you also know that zinc finger is a protein "motif" that, in a manner of speaking, plays tunes on the DNA by binding to it to initiate transcription of specific genes?

You can find out almost everything you always wanted to know about the state of molecular biology in the Encyclopedia of Molecular Biology. There are more than 5,500 entries, over 200 of these being long articles on rapidly moving subject areas written by recognised authorities in the field, making it a hefty volume. This is the book almost every biologist ought to have.

The volume is intended to "help those both inside and outside the field to understand the methods, concepts and findings of molecular biology . . ." That is a tall order. I have sampled the long entries, including topical items such as genetic engineering, gene therapy, fingerprinting, human genome project, oncogenes (genes implicated in cancer), transmissible spongiform encephalopathies (a group of degenerative diseases of the central nervous system related to mad-cow disease). While all are well-written and handsomely illustrated, the thicket of terms is enough to intimidate all but the most determined. The volume serves those who already have background knowledge, equivalent to at least a first- or second-year undergraduate course in biology. For others more advanced looking for detailed information, the volume provides a useful first overview to whet the appetite. I found it a compelling read, and as soon as I had finished one entry, I was turning the pages to dip into another.

But it is not the volume for everything one wants to know about molecular biology, since it is all too much about genes and not enough about biology. Even though it covers a wide range of biological topics, such as pattern formation and the embryonic development of many laboratory organisms, the emphasis is predominantly on the genes involved. Indeed, as the techniques of molecular genetics are transferred to all disciplines, from developmental biology to ecology, the reductionist mind-set that accompanies the techniques has infiltrated throughout biology, displacing all holistic or organismic approaches. It also excludes many chemical and physical aspects that have formed an integral part of the subject matter of molecular biology since its beginnings in the 1930s. This has had a drastic effect, not just on research, but on the education of biologists in general. Try striking up a conversation with any of the new breed of molecular geneticists - young, brash and mostly male - and nine times out of ten, you get the impression that he is speaking and thinking like he sequences DNA: linearly and in one dimension. His idea of tackling any problem in biology is to "find the gene".

As the general editor of an advanced Open University course, "Living processes", which is about molecular and cellular biology, I was disappointed that a significant number of topics and concepts in our course have failed to make it into the encyclopaedia, a notable omission being etabolic control analysis. By contrast, the entries for molecular genetics are quite comprehensive. As a lapsed molecular geneticist for the past six years, I scored only two misses: concerted evolution and directed mutation. The comprehensive coverage of molecular genetics as opposed to molecular biology in the volume is an indication of the extent to which the former has taken over all of biology. That is a pity, for it happens just when molecular biology itself is becoming more holistic and systems oriented.

Finally, there is a group of people for whom a volume like this is compulsory - those who wish to keep abreast of the subject in our present age of gene biotechnology. Not only has genetic engineering taken over biological research and teaching, it has become big business as biotech companies team up with molecular geneticists to exploit the fruits of their labour. Genetically engineered hormones and drugs, transgenic crops, diagnostic tests, gene therapy and so on, are being made commercially available as opposition is gathering over many applications of gene biotechnology.

For instance, do we need more screening tests for yet more diseases? In the United States, people who have tested positive are already being discriminated against in employment and in getting health insurance. Similarly, a positive result in prenatal diagnosis can place parents under social and economic pressures to abort the foetus whether they wish to do so or not. The patenting of transgenic organisms, human genes and human cell lines raises moral and ethical concerns worldwide about reducing life to a commodity.

A related issue is the intellectual property rights of farmers in the third world, as among the patents are seed varieties and knowledge of their uses belonging to the farmers that have been taken from them without recompense. Are genetically engineered food products safe? I read in the encyclopedia that a gene coding for a powerful insect toxin is transferred to crop plants and made to express at high levels. Might that not harm people as well as other non-pest organisms? Do transgenic crop plants pose a threat to biodiversity? Again, in the encyclopaedia one reads that at least two classes of animal viruses have wide host ranges and can infect invertebrates as well as plants. Could these not act as vectors for transferring genes between transgenic crop-plants and insects, and via those to other plants? As disease-resistance and herbicide-resistance genes are incorporated into crop plants, could these not get transferred into weeds, turning them into super-weeds? Another piece of information on plant genetic engineering I gleaned: ". . . it is not yet known to what extent maintenance or expression of the transgene is stable in the genome . . ." Does that mean transgenic crops may not only be dangerous but commercially non-viable as well?

These are examples of the sort of things that worry sceptics of gene biotechnology as a worldwide programme to promote applications in nutrition, health and the environment is being considered in the United Nations. While the potential hazards and the socioeconomic problems have been identified by the critics, the proponents have been slow to substantiate the claims of actual and potential benefits. It is high time the pros and cons of the applications of gene biotechnology are publicly debated.

The Encyclopedia of Molecular Biology gives valuable access to the scientific information necessary for such a debate. It should be made available electronically on CD-ROM for ease in updating, which would presumably offer a saving on its present hardcover price of ?99.50 - and on backaches from carrying it around.

Mae-Wan Ho is director, Bioelectrodynamics Laboratory, Open University.