Molecules, DNA and the potential of stem cell research

Posted in Historical articles, Medicine, Science on Thursday, 19 April 2012

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This edited article about molecules and DNA originally appeared in Look and Learn issue number 691 published on 12 April 1975.

War on Want airlift, picture, image, illustration

Starvation follows disasters and famine, which is when War on Want delivers much-needed aid to the people on the ground, by Angus McBride

Britain has a population of about 55 million people. Is that a dull fact which fails to raise a flicker of interest? Well, here is something to make you sit up. Multiply that figure by ten and you have an idea of the number of people who are suffering from one of the deadly ailments of our age – starvation.

Most of the hungry millions live in India, Bangladesh, Java, Egypt, the Middle East, the western Sahara, the Caribbean and Brazil, and along a line drawn along the Andes from Chile to Mexico.

They are starving because they are eating too little food which contains protein, the vital substance which builds and sustains our bodies.

In the West, we are conscious of this problem – who is not? – and scientists are doing their best to solve it by finding ways of making proteins from other things. Oil is one of them. It has been found possible to make proteins in oil refineries by turning one of the by-products, wax, into these.

Proteins can also be made from the bones, skin and heads of fish, from seaweed, from sugar cane (after the sugar has been extracted) and from potatoes, sugar, fat and other cheap foods which normally contain little or no protein.

Mixed with flavouring substances, this protein can be made into an acceptable food for the people in the countries where it is so badly needed.

Another way of solving the world food shortage is to grow more food. This is a glib statement. But we can only grow more food if we know how to cultivate better crops. This is another field in which scientists are working.

They are trying to get a better understanding of how a plant uses sunlight to help it to grow. This is called photosynthesis and it enables the plant to turn the things it gets from the soil and the air into starch, oxygen and other things.

To see how this is done, the research workers make the soil in the plant’s pot radioactive. This puts something into the soil which gives off invisible rays. As the plant absorbs goodness from the soil, it also absorbs some of the radioactivity. This is measured with a Geiger counter which tells where the things from the soil have gone to in the plant and in what quantity.

In this way, scientists can see how plants make more and more cells in order to grow. You can see a drawing of the cells of a water plant on the left.

All living things are made of these tiny things called cells which divide and thus make more cells. The centre of the cell is called the nucleus and inside that is the nucleolus containing the chromosomes. These are the things which enable a cell to make a replica of itself. Half of the chromosomes in each of your cells come from your mother and half from your father. And when you become a parent, you will pass on a set of chromosomes to your child so that it will have some of your characteristics and some of its other parent’s. At the same time, both parents will pass on some of the characteristics of their parents.

This is called genetics, and a plan to show how a child inherits something from past generations in its family was drawn up. Called a genetic code, it was worked out after scientists had studied things in the nucleus of cells which they named nucleic acids. These are made up of chains of compounds which are known by initials like RNA and DNA.

The work of the nucleic acids is to pass on inherited qualities to the next generation and to build up body proteins.

Lord Todd of Cambridge University was awarded the 1957 Nobel Prize in Chemistry for his work on the structure of nucleic acids. And for their researches which showed how a molecule of nucleic acid (called DNA) is constructed, the 1962 Nobel Prize in Physiology and Medicine was awarded to the Britons F. Crick and M. Wilkins and the American, J. D. Watson. With this knowledge, an American team led by Arthur Kornberg found a way of making DNA in a laboratory.

Two things have made this research possible. One is an electron microscope which enables objects to be magnified so greatly that small structures inside a cell and even large molecules can be photographed.

The other is the use of radioactivity, the system we mentioned earlier which makes an object give off invisible rays. A molecule – the smallest particle of any substance which can exist independently without changing chemically – can be made radioactive. What happens to it as it enters a cell can then be studied with an instrument which detects its radioactivity.

This is a vital study because living tissue is made of carbon and hydrogen atoms, often with other atoms. These join together to make molecules, and the molecules from cells. In turn, cells of similar kinds join together to make the different parts of our bodies or the flowers and leaves of a plant.

Living bodies are maintained and kept in repair in this fashion. This brings us back to the question of food. Only if we eat the right food with the correct amounts of carbohydrates, fats and proteins can our bodies make new living tissue.

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