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DNA basics

Deoxyribo Nucleic Acid (DNA) - otherwise known as the "secret of life" or the "building blocks of life". DNA carries the genetic instructions for life, coding for proteins that we depend on to survive as well as passing on characteristics from one generation to the next.

This year we celebrate the 50th anniversary of the "double helix" structure of DNA, proposed by two scientists called Watson and Crick in 1953. This discovery was the beginning of an exciting new level of understanding of how living things work. It meant that scientists could now understand how DNA copies itself so the genetic codes and the resulting characteristics, such as eye colour, are passed on from generation to generation and how proteins we need to live are made.

All living things are made of DNA - plants, animals and humans, and it is the small differences in the DNA code that makes us different from one another and makes species different from each other. Although we only fully understood this in the last 50 years, we have been changing the makeup of plants and animals for centuries. Man began to domesticate plants and animals by choosing those with the most desirable traits - such as those that produced the tastiest, largest grain or most milk, contained the least amount of toxins and were resistant to disease etc. This "selective breeding" was the beginning of the process of transforming a few wild plants and modifying them into useful and nutritious food crops. Today, we know these as maize, soya, potatoes, tomatoes etc, and all of them have very little in common with their wild ancestors. Without understanding the science behind it, early man selected certain 'desirable genes" that coded for specific characteristics and selected against undesirable genes. Things became clearer in the late 19th century with the work of Gregor Mendel which explained how characters were inherited. Efforts became more focused on overcoming specific diseases and problems in the years that followed, and also focused on the production of medicines, such as penicillin.

This use of living things that began centuries ago to make useful products is called biotechnology. The discovery of the DNA structure in 1953 led to an explosion of research and the development of modern biotechnology. In a way, modern biotechnology is a continuation of the modification process that began with crop and animal domestication - but through a process called gene transfer. Traditional breeding involves crossing two organisms from the same or closely related species to combine desirable characteristics, but gene transfer cuts across the species barrier. In gene transfer, which takes place in a laboratory, a specific gene for a desirable characteristic can be inserted into a completely, non-related individual - and so the DNA is recombined. Unlike traditional breeding which can take many years to obtain the desired result, gene transfer is immediate. Gene transfer, along with cloning, are the more controversial technologies of modern biotechnology. However, there are many applications which are not so controversial and that have been a part of our everyday lives since we were born - our food, water, medicine and shelter all require biotechnology at some level. Uses of modern biotechnology include: making medicines in large quantities such as antibiotics and human insulin for the treatment of diabetics; combating crime through DNA and forensic testing; removing pollution from soil and water (bioremediation); and improving the quantity and quality of agricultural crops and livestock products.

So, DNA may be small and seem somewhat insignificant, and yet it is the basis of life upon which many technologies are based and depend upon for life, as we know it.

Young Science Communicators Writing Initiative:

In an initiative to offer a platform to exercise skills in science communication, PUB commissioned a group of young scientists to write popular articles on various topics relating to biotechnology applications. Read their on articles on topics including sustainable energy, aquaculture, palaeogenomics, and more... Click here to view.


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