The moment I saw the model and heard about the complementing base pairs I realized that it was the key to understanding all the problems in biology we had found intractable - it was the birth of molecular biology.

I went in with Jack and Leslie, into this room that was lined with brick, and there on the side I can remember very clearly was this small model with plates for the bases - the original model with everything screwed together.

He told me that Francis Crick and Jim Watson had solved the structure of DNA, so we decided to go across to Cambridge to see it. This was in April of 1953.

In my second year, after moving to the Medical School, I began the courses of Anatomy and Physiology. I had begun to see that I was interested in cells and their functions.

At that moment, I saw it in the skating lounge. I just heard the audience scream and I saw the people laying on the ice. I just tried to stay far away from that emotionally and not get involved inside.

We have to accept that we are just machines. That's certainly what modern molecular biology says about us.