The chicken, the egg and the molecules – Machine tools of life (1980)

David Phillips

In the second lecture in the series, Sir Phillips investigates the power of enzymes.

Watch time: 58:33
A close up of a man holding a clear cube
Image credit: Royal Institution

Lecture 2 – Machine tools for life

From the lecture programme:

Nearly all of the chemical reactions that take place within a living organism are under the control of protein molecules. These protein molecules are known as enzymes and they act as catalysts, controlling the rate at which the chemical reactions take place without being changed themselves. In general, each individual chemical reaction, which might be concerned, for example, with breaking down food molecules into smaller pieces, is controlled by a separate enzyme.

Enzymes and the molecules whose reactions they control have complementary shapes and fit together like jigsaw puzzle pieces. In order to understand how enzymes work, it is essential, therefore, to know their shapes. We shall see how X-rays can be used to study the three-dimensional structures of protein molecules in crystals and how these methods were used at the Royal Institution to work out the structure of an enzyme molecule for the first time. The enzyme was lysozyme from egg-white, which has the ability to kill bacteria, and the studies also showed how it works.


Which came first, the chicken or the egg? This is one of the best known of all riddles without an answer but it is now giving place to a new riddle about the molecules from which chickens and eggs – and human beings – are made. These molecules are proteins and nucleic acids.

This series of six lectures, five presented by David Phillips and one with Max Perutz, showcases the complexity and importance of the proteins that make up so much of life. The lectures weave through the DNA helix, unravelling the mechanism that links DNA and protein production, and asking ‘which came first, the DNA or the protein?’