The Human Genome
How do you visualise DNA? Think of a simple work ladder (somewhat buckled!). What is The Human Genome Project all about? Could this new line of research really 'cure'inherited diseases? What else does the future hold?
From time to time in the news media, you might have noticed people getting excited about newly-discovered genes - a gene for breast cancer, a gene for a muscle disease, and so on. It seems that this new line of research could not only 'cure' some inherited diseases, but it could dramatically change how we look.
The story begins with DNA, which is actually the blueprint for a human being. DNA stands for deoxyribonucleic acid. It's a collection of atoms, which are arranged to look like a long ladder, with rungs joining the side rails. It's a very long ladder, with about 3 billion rungs. This DNA, the very long ladder, is in each cell in our body, except for the red blood cells. The DNA is all coiled up very tightly to fit inside each cell, but if you were able to tease it out, it would be a few metres long.
There are three billion rungs in the DNA ladder of life, but these rungs are not all identical. There are four different rungs, called either A, C, G or T. One great discovery was that a set of three rungs contains the information to make one amino acid. So the set of rungs AAA will make one amino acid, while the rungs ACG will make a different amino acid. When these amino acids join together they make proteins, and these proteins can speed up chemical reactions. And finally, these chemical reactions make flesh and skin, blood and bone, brain and liver - and everything else you need for a new human being.
And a gene? Well, that's just a big collection of these sets of three rungs that does a specific job, like making nerves, or making collagen. We know that there are about three billion rungs on this ladder of life, the DNA, but it's only in the last few years that we have begun to map them all, with the Human Genome Project. The word 'genome' just means the sum total of all of the rungs of the ladder. The Human Genome Project will be finished around the year 2000-or-so, and already we have discovered a few interesting genes along the way.
But the real excitement will come once we have the total map of the entire human DNA. A general rule in many fields of science is - "The Map defines the Territory". Let me give you an example.
Around the early 1900s we began to have the first accurate maps of the continents, and of the off-shore underwater continental shelf. In the early 1920s, a meteorologist called Wegener played jig-saws with little paper cut-outs of the continents and the continental shelf, and found, for example, that Africa would slot nicely into South America. And so today we have the theory that the continents drift around the surface of our planet, sometimes running into each other, and sometimes moving apart. Because Wegener could look at the whole map of the Earth, he could gather more knowledge, and this led to a new theory.
In the same way, once we can look at the whole map of the blueprint of life, the DNA, we will make new discoveries. Let's look at wrinkles. You get wrinkles because, sometime in your 20s, the machinery that makes collagen switches off. We might be able to switch this machinery on again, so that we can face the future, wrinkle-free. Who knows, we could even use our new knowledge of the DNA to live longer, or to remove some of the 5,000 currently-known inherited diseases that plague us, such as cystic fibrosis.
Now when a car comes out of a factory, it has no knowledge of who made it or how it was made, and it certainly can't change itself. But for the first time in the history of the human race, we are beginning to understand how we are made - and so we might be able to change ourselves.
One Nobel Prize-winning physicist claimed that the best shape for a human being would be a cloud of iron vapour, weighing about 60 kilograms, and about the size of our planet. Now he was just letting his imagination roam free, but he said that this shape had many advantages. You could travel through space without any external machinery or propulsion, you could still communicate with your fellow humans who had the traditional two arms and legs, and best of all, while you could still vote, nobody could make you pay taxes!
But before we go to those extremes, we should be able to cure some inherited diseases.
Published 24 May 2000
© 2024 Karl S. Kruszelnicki Pty Ltd
