The strings that tie us up;Science in the curriculum;Edinburgh International Science Festival

5th March 1999 at 00:00

As the Association for Science Education meets in Aberdeen, we report on innovative projects around the country

The resemblance between a human being and a brick wall is not apparent to most of us. But a biologist looks beneath the surface, and observes that humans are built from cells just as walls are built from bricks. And that both are constructed according to a plan.

"Inside each cell in our bodies is the nucleus and that's where we find the plans, which are called genes," explains Dr Duncan Borthwick to the pupils at Garrowhill primary school, Glasgow. "Genes are made of a stringy chemical called DNA."

He repeatedly twists a length of string to show how DNA becomes supercoiled so it can fit inside a cell.

"All our DNA is in little packages like this called chromosomes and each cell of our bodies contains enough, if it was unwound, to stretch from here to Moscow."

Genes, he explains, are the reason some of us have fair hair, others dark, some have blue eyes, others brown, some are boys, others girls.

He demonstrates how each baby gets a different scoopful of genes from mum and dad, which is why siblings usually turn out differently. Identical twins, like Louise and Kirsty at the back of the class, have exactly the same genes because they developed from a single cell.

But genes are only part of the picture. "I got my Dad's genes for height," says Dr Borthwick," but I wouldn't have grown tall if I hadn't been well fed. And some people seem to be natural athletes but they also train hard, eat the right kind of food and get plenty of sleep.

"Lots of things affect us in our lives besides genes, and it's important to remember that."

For the next section of the show the scientist enlists the help of Rupert, a skeleton who is looking cool in baseball cap and shades. "Bones are alive," says Dr Borthwick. "They are light and strong because they are hollow like the frame of a bicycle. And they do lots of different jobs."

He compares the little bones in our ears with the large ones in our thighs. Then he uses Rupert, X-ray images and a short aerobics session to illustrate how bones work together, what their shape reveals about their function, and how we can protect and nourish them.

The show is lively, interesting and relevant.

"Our teacher did a project last week about how your body works," says Kirsty. "But it doesn't quite give the whole story."

"I enjoyed the show," says Louise, "but there's something about twins he didn't tell you. Being one is really annoying."

To book for Living Skeleton and Ingenious Genes, which is aimed at P4-P7, telephone the EISF box office on 0131 473 2070.

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