Imagine how useful it would be if tomatoes could be grown on the stalks of potato plants. Two crops could be
grown at the same time, using the space of one. Or imagine how marvellous it would be if inherited diseases like cystic
fibrosis and haemophilia could be eliminated. Both possibilities are now conceivable because of an important
new technique called genetic engineering. It is as important a development as the silicon chip, with
hundreds of new applications - and it involves being able to control the very basic design of life itself.
All living things, from the very simplist bacteria to a complex creature such as Man, are made up of living cells.
In the case of a human being, millions of them. And every living thing has the ability to reproduce itself.
People grow up from babies into adults as their cells continuously produce new and slightly changed cells.
The changes go on as we grow older and eventually die - when the cells no longer reproduce at all. All the
changes that happen throughout our lives are not random or accidental. Every person has a unique plan or blueprint
that was drawn up from the time he or she was conceived. This plan determines the colour of eye or hair and,
how tall we may grow, or may be even how intelligent we are. This personal blueprint is stored inside every
Inside the nucleus of every cell are tiny thread-like bodies called chromosomes. They exist in pairs: normally
human beings have twenty-two pairs of chromosomes, and two odd ones in each cell. These chromosomes are made
of a complex chemical called DNA - short for deoxyribonucleic acid. This chemical carries the details of the
plan or blueprint, each tiny piece of which is called a gene. There are genes to decide hair colour, others to
decide eye colour, and so on. If a living cell happens to be part of an eye, it will make active use of the
eye colour gene. In each cell, therefore, there is a complete string of genes, even if it 'uses' a few of
Basically a string of genes is like a string of numbers. So that one person's genetic code might look something
like 22134211134421243341... while another will look like 2213421113442124332122. This is where the amazing new technique
of genetic engineering comes in. Even though every living cell is microscopic in size, and the chromosomes are smaller
still, so that the genes on them are so tiny that it is hard to believe that they could be sorted out and identified,
scientists have now developed such sophisticated techniques that they can identify many precise details of the
For instance, they might demonstrate that there were five digits in all genetic codes on one particular chromosome and its twin,
to determine the way in which our blood clots when we cut ourselves. And since the chromosomes are in pairs, they may be able
to discover that when, say, the digits 1 and 2, as the first digits of the five, on one chromosome are paired with,
say, 3 and 4 on its partner, it produces a problem: the blood does not clot. Literally hundreds of thousands of number
combinations would be fine - such as these pairs:
a. 12433...+ 33122...
b. 43122...+ 41333...
c. 22143...+ 41122...
but this pair: 12134...+ 43314...
has the fatal combination of genes leading to a failure of blood to clot - the disease haemophilia.
Genetic Engineering is the name given to a range of techniques by which scientists can actually
manipulate these number codes. As they learn more about our genes and how to control them, is looks as though it will
only be a matter of time before they can manipulate the numbers in the haemophilia-causing genes, so that
the problem disappears.
1. Are the potential benefits of genetic engineering greater than the dangers? Form your own opinion.
2. Think of other uses not mentioned in the text which could be made of genetic engineering, either positive or negative.
3. Would you like to be able to select the kind of children that you might one day have: their sex, looks, personality,
level of intelligence etc.? Why (not)?
Source: Step Up , Diesterweg Verlag, 1991, pp. 112-114