The topic of genetic engineering offers teachers an opportunity to engage students in an area of biology that is developing fast, and at the cutting edge when it comes to using technology. It is an area of science that is much in the public domain through issues such as the development of genetically modified (GM) foods. The human genome project is designed to work out the complete code of the human genome. Knowing the complete code will open a new era in treating and finding cures for diseases which in the past have been difficult to cure. There is also debate on the ethical aspects of genetic engineering in humans and plants.
The molecular biology involved in manipulating DNA is fascinating and yet difficult to replicate in the classroom. There are misconceptions about what genetic engineering sets out to address. Terms like 'designer babies' in the media have contributed to the misconceptions and a poor understanding of this area.
Genetic engineering is the scientific alteration of genes or genetic material to produce desirable new traits in organisms or to eliminate undesirable ones. It means removing a gene from one living organism and putting it into another. Organisms can be genetically modified to produce substances that are of direct use to humans, such as insulin for treating diabetes. Another area of development has been the production of GM foods. The range of GM foods is extensive, including vegetarian cheese, tomato purée and soya. There has been a lot of debate recently over the safety of growing GM food.
It is important to understand the molecular process involved in genetic engineering. Bacterial circular DNA, known as a plasmid, is central to genetic engineering and is used to 'carry' the gene that is used to modify an organism or to produce a useful biological protein such as insulin. The gene of interest, for example the human insulin gene, is inserted into the plasmid using special enzymes called restriction enzymes, and ligase, which 'sticks' the sequence in. There are many types of these enzymes and each recognises a different DNA sequence where it makes the cut. This gives scientists control of where the gene of interest is inserted.
It is important that we make informed judgements about the economic, social and ethical issues concerning the use of genetic engineering, and use correct terminology when describing the different stages involved in genetic engineering.
There is a misconception that genetic engineering is used to make designer babies. Students are not clear what the term recombinant DNA (a form of DNA produced by splicing together segments of DNA from two or more organisms) means, although it is central to genetic engineering. There is also some confusion when using the terms DNA, chromosome and gene. The function of restriction enzymes and bacteria generally are covered very briefly and students do not get an opportunity to fully understand how recombinant DNA is created and later isolated. Students do not understand the different types of 'cut' produced and the various enzymes that facilitate genetic engineering.