They wanted the chance to practise the techniques, hear about the latest research and discuss with experts the ethical implications of the most dynamic and fast-moving area of modern science.

“This is a very effective form of staff development,” Jack Jackson, HMI with national responsibility for science, said. “You take teachers out of the work environment for a substantial block of time, away from pupils and pressure of work, and immerse them in the subject that really interested them all those years ago when they went through initial training.”

Denyse Kozub, the curriculum council’s assistant director, said: “For some teachers the last time they studied biology was 25 years ago when there was really no such thing as biotechnology.”

The summer school is in its second year. It is heavily sponsored by Unilever and the curriculum council, while Edinburgh University provides the facilities. Biotechnology forms part of Higher Still courses from Intermediate to Advanced, and there is to be a new Higher in the subject.

Richard Langridge, biology teacher at Inverness Royal Academy, says he found the course concentrated but enjoyable: “When I was at university, we learned the double helix structure of DNA and that was about it.

“A lot of my students will be going into biotechnology courses, so I would like to be able to give them some idea what they are letting themselves in for. And I want to be able to correct some of the misconceptions the kids have. Many of them get their knowledge of science from the X-Files.”

But for some of the teachers, the idea of updating knowledge acquired in the biological dark ages seems somewhat premature because they look as if it will be a few years yet before their knowledge starts dating. Although Corinne Digges has just completed teacher training at Northern College, Aberdeen, she still found the summer school valuable because progress in biotechnology is so rapid and it is some time since she studied genetics.

Ms Digges says: “We had lectures on cancer research and the human genome project, and we went to the Roslin Institute where they told us about their research and we got to see Dolly the sheep and her lambs. They were all sitting around eating hay, and they looked fine, quite normal.”

Dean Madden, of the National Centre for Biotechnology Education in Reading, told the teachers who will soon be telling their pupils: “Normal is a funny old word. As the human genome project progresses, we will find it increasingly difficult to refer to things as normal. Research published just last week showed there is a great deal more variation in genes than we ever imagined.”

Then he turned to the practical: “I want you to take your pipettes, suck up five microlitres of restriction enzyme and add it to . . .”