Middle class shudders at superman spectre

THE ISOLATION of a group of pure genes from a microscopic, but living, organism constitutes a major step forward in our understanding of the origin of life and the causes of inherited diseases.

As was to be expected, this advance in the science of genetics, carried through by a team of young research workers in the Harvard Medical school, has sent shudders through the middle class by raising the spectre of supermen, that is, the possibility of breeding human beings to some pre-selected specification.

The cries of protest in defence of the sanctity of the individual, which are emitted on these occasions, is the defence of the 'divine right' of millions to die of disease and starvation.

However, genetics is still a very young science and the sort of 'genetic engineering' involved in changing the characteristics of humans (or even plants) is still some way in the future. the proportion of three to one.

There is a huge gap between the manipulation of mammalian cells and the bacterial cells used by the Americans.

As 'The Times' expressed it: •.. the progress by the American team makes the same contribution to genetic engineering as Newton's formulation of physical laws did to the landing of men on the moon.' GOLGI BOD OȘOME NUCLEAR MEMBRANE by Inevitably, the study of ing organisms has lagged behind that of inanimate jects.

For thousands of years, reference to the Bible or other religious writings was considered sufficient in answer to the question: 'What is life?' Even to consider the possibility of a scientific investiPINOCYTIC' VESICLE CYTOPLASM CENTROSOMES NUCLEUS® 0 ENDOPLASMIC I RETICULUM UCLEOLUS MITOCHONDRIA CELL MEMBRANE gation was heresy.

The division between living and non-living matter was considered absolute.

Man was possessed of the divine 'vital force' and fashioned in the image of God.

Even Kepler, who perceived the orbital motion of the planets over 350 years ago, thought that fish could arise by spontaneous generation from salt water of the seas.

Even Darwin, whose theory of evolution was based on the assumption of the existence of heritable variations among individuals of the same species, knew nothing about the pattern that heredity follows.

Ironically, while Darwin was writing in 1872 that 'the laws governing inheritance are for the most part unknown', the answers had been revealed six years previously by Mendel, a Silesian monk.

Genetics

It was not until 1900 that his work became known and it was realized that 1866 had seen the establishment of genetics as a science obeying objective laws.

It it worth while describing one of Mendel's investigations in detail.

Mendel studied the effects of the crossbreeding of two plants endowed with contrasting traits. If red-flowered and white-flowered peas were allowed to self-fertilize, with no possibility of cross-feritilization, the plants yielded seeds which bred true to type-red or white, like their parents.

However, when cross-fertilization took place, he found that all the seeds gave rise to red flowers, but when this new generation of red flowers was cross-fertilized, seeds were ing, is sufficient to explain Mendel's results-three red peas to one white.

As over a thousand plantings had been carried out initially, there was no possibility that this was a chance result.

Precisely the same proportion was revealed of tall to short plants in a further investigation.

Mendel correctly concluded that there are factors in peas which determine their colour and height. These factors became known as genes and are transmitted by a single pollen (or sperm in the case of animals).

The factor for redness or tallness is dominant, in that it asserts itself over the recessive gene (whiteness or shortness).

Why are some genes dominant and other recessive?

As yet, the detailed mechanism is not known, but with this assumption it is relatively simple to explain Mendel's results.

fertilization:

Genes White fertilization Gene pairs White-red White-red The concept of dominance, together with that of gene pairCombinations white-red Combination:

During the 100 years following the publication of Mendel's findings, scientists have slowly pieced together the molecular mechanisms which unerringly achieve the transmission of heritable traits to the offspring.

The discovery that all the larger organisms, animals and plants were composed of cells was a great landmark in the history of biology. It was effectually completed by Pasteur when he showed that all cells, even the smallest single-celled bacteria, are produced by other cells.

An up-to-date picture of the cell, as revealed by the latest electron microscopes, is shown below.

It would need 5,000 such cells to cover one full-stop on this page!

This only emphasises the enormous refinements in technique that were necessary before the constituents of the cell could be analyzed in detail and their role in the reproductive process established.

The cell membrane is broken down either by mechanical grinding with some abrasive substance, sonic vibration or dissolved by an enzyme (the protein 'trigger' which sets off a reaction).

Components

The cell's contents are then exposed to 100,000 times the force of gravity in a centrifuge. As the rotation increases, the various components of the cell sediment out one by one and can be collected for individual examination.

The two major questions are: what are the roles of the cell's constituents?

How are the basic molecular building-blocks duplicated in the process of replacement of worn-out cells and in the reproductive process, during which the cell 'grows a second set of innards' and splits to form two cells?

The cell membrane recognizes with its molecular memory the hundreds of compounds swimming around it and permits or denies passage according to the cells requirements.

The function of the mitochondrion emerged in the early 1950s as the furnace of the cell: It embodies 40 enzymes which process glucose and store its energy in a form readily usable by the cell—a kind of molecular battery.

It also burns up fragments of worn-out cell components and it has been established that most of the molecules of which our bodies are composed are completely renewed once every few days!

Within the cell's nucleus reside the chromosomes, thread-like bodies containing protein and the fundamental hereditary material, DNA, one of the nucleic acids.

They are found in all cells and in primitive organisms, e.g. bacteria, all the genes are located in a single chromosome:

In higher organisms the full complement of genes in a cell divided among several chromosomes.

In addition, each chromosome occurs twice, so that there are two pieces of genetic material controlling a given

white-white white-red red-white red-red led) 'gene pairs', referred to above in connection with Mendel's laws.

When a cell divides, the genetic information embodied in the DNA is passed on to the two daughter cells during this process.

Each chromosome is duplicated, drawn to opposite sides of the nucleus, which then splits, followed by the rest of the cell.

The pinpointing of DNA as the basic hereditary material took place in 1944, but it was not until 1953 that Watson and Crick put forward their famous double-helix model for DNA-like two intertwined springs.

Replication takes the following way.

The two strands separate like the two halves of a zip. Then each half fashions a new 'mate' for itself, using its old 'mate' as the model.

Appearance Appearance white Thus the exact replication of DNA (and therefore the gene) is ensured.

How does the DNA spell out its instructions for the building of a particular protein molecule?

The problem of 'decoding' DNA seemed enormous. It was calculated that the storage of information for the proteins of a bacillus would require a closely typed 3,000-page book!

Code cracked

However, without going into further detail, it is, perhaps, sufficient to relate that the code was cracked in 1961, but that there still remains much confusion over its validity.

The superb technical feat that Dr Jonathan Beckwith and his colleagues have performed at Harvard is the isolation of a specific gene from a specific bacterium.

Now that the technique has been proven, it can readily be applied to other genes.

Why is this important?

One thing is certain. If only one letter in the genetic code is incorrect, the result can be fatal for the living organism— cancer or some equally destructive disease may result. A model of the DNA molecule with the 'intertwined springs' of phosphate-sugar chains surrounding base pairs.

Conversely, a further refinement of technique may see a cure for such 'natural' scourges through 'genetic engineering'.

Why did Dr Beckwith call a press conference and express his dismay at the possibilities for genetic manipulation?

The 'New Scientist' says that it is not only the skills of scientists that worry him, but also the proven ineptitude of governments in applying them'.

No doubt there are many like Dr Beckwith who realize, if only superficially, that imperialism can turn man's greatest scientific achievements into weapons of destruction.

Destruction

It is ironical that Nixon proposes the destruction of bacteriological weapons at the same time as American scientists put within the grasp of his masters the means for blueprinting viruses against which there can be no defence.

The full implications of 'genetic engineering-the freeing of mankind from disease and the conscious improvement of his physical and mental qualities-can only be realized when he is liberated from the day-to-day battle for the basic necessities of life.

It is this task that the socialist revolution must carry out.