Cloning 2 Essay, Research Paper

Cloning

Of all the terms coined by scientists which have entered popular vocabulary, ‘clone’ has

become one of the more emotive. Strictly speaking a clone refers to one or more offspring

derived from a single ancestor, whose genetic composition is identical to that of the

ancestor. No sex is involved in the production of clones, and since sex is the normal means

by which new genetic material is introduced during procreation, clones have no choice but

to have the same genes as their single parent. In the same way, a clone of cells refers

simply to the descendants of a single parental cell. As such, adult organisms can be viewed

as clones because all their parts stem from the single cell which is the fertilised egg.

Likewise, many tumours are clones, derived from one aberrant cell which no longer obeys

the normal rules of growth control. The offspring of organisms which reproduce asexually,

like corals, are also clones; as are identical twins produced by the natural, or sometimes

deliberate, splitting of a single embryo. Members of a clone are genetically identical and

genetic identity has given cloning an additional more technical meaning: namely the

procedures used to create a new organism whose genetic constitution is a replica of

another existing individual. Such a feat can be achieved by substituting the nucleus, which

contains the genes, from one of the cells making up that individual’s body, for the nucleus

of a fertilised egg.

Since our genes dictate to a large extent what we look like, how we behave and what we

can and cannot do, having identical genes, as identical twins do, ensures something more

than mere similarity. Novelists and film makers have not been slow to exploit the imagery

afforded by cloning. Limitless numbers of identical beings manufactured from existing or

previous generations has obvious dramatic potential, although seldom of a reassuring

nature. Clones traverse the cinema screen as crowds of dehumanised humans destined for

monotonous drudgery, as invincible armies of lookalikes from outer space, as replicas of

living megalomaniacs and, in the ultimate fantasy, as the resurrected dead – troupes of little

Hitlers and herds of rampaging dinosaurs. Of course, this is science fiction. Nonetheless

there is just a whiff of plausibility, a whisker of scientific credibility; enough to plant an

indelible vision of what might be, or even what could be.

So it is easy to understand why the arrival earlier this year of Dolly, the sheep developed

from an egg whose own genes had been replaced by those from an adult udder cell, was

seen as the first incarnation of a sinister future. Dolly was a clone of the sheep (her genetic

mother) who provided the udder cell. The package of genes in the nucleus of that udder

cell contained exactly the same repertoire of genes as all the rest of her mother’s cells and

so Dolly’s genetic makeup was to all intents and purposes identical to her mother’s. No

sperm had had the opportunity to add its genetic pennysworth. However, there was

nothing radically new, neither technically nor conceptually, in the way in which Dolly was

made. Almost all films and documentaries on cloning still show the same footage, produced

more than twenty-five years ago during unsuccessful attempts to clone rabbits, of a nucleus

being injected into an egg. What was novel about Dolly was that she was the first

unequivocal mammalian clone. Lower vertebrates had been cloned in the early 1960s

when it was shown that a nucleus taken from an adult frog cell transplanted to a frog egg

whose own nucleus had been destroyed was able to direct the development of that egg

into a swimming tadpole. Indeed, it was this experiment that first indicated that the genetic

content of all our cells, despite the profound differences between a skin cell and kidney

cell, must be more or less the same and retain all the genetic information necessary for an

egg to develop into a whole organism.

While cloning can offer the scientist important answers to fundamental questions about our

genes, it has a much older and very natural history which long precedes the sophistications

of the modern laboratory. The word ‘clone’ comes from the Greek klwn, meaning twig,

and there is a very good reason for this. For example, every chrysanthemum plant you buy

at a Garden Centre is a clone of some distant and probably long dead chrysanthemum

which once supplied a side-shoot for rooting. Likewise, whenever you divide an

overgrown shrub or successfully cultivate a houseplant cutting you are cloning. In each

case you are deliberately propagating a copy of the parent, and eventually over successive

years and many hours in the greenhouse, producing a multitude of plants (clones) all

genetically identical to the prized parent. Elm trees and other suckering plants clone

themselves naturally, sending out subterranean roots from which new plants, of identical

genetic constitution, will sprout. Deliberate cloning is as old as horticulture itself. Thousands

of years before anyone understood the physical nature of heredity, specific genetic

constitutions were preserved through cloning because they bestowed on the plant desirable

qualities such as disease-resistance, high yield and predictable growth. Cloning is as

important to the production of fine wine, the supply of rubber and the fruit harvest as it is to

the variety of an English country garden. Furthermore, natural cloning is not confined to

plants: microbes and some insects frequently propagate themselves by producing

genetically identical offspring without recourse to sex. The toothless mammal, the

armadillo, gives birth not to identical twins but to genetically identical octuplets: every litter

a batch of eight clones. There is nothing a priori unnatural about cloning.