Lecture 5 – In the hands of the giants

From the 1992 lecture brochure:

All the molecules we have talked about so far have been smallish with 100 atoms or less. We are surrounded - literally - by giants, frequently with a million atoms or more, which can be man-made, or 'natural'. These giants share the property of being constructed with repeating units. In this talk we examine those handed giants - carbohydrates and proteins - whose building blocks are glucose and amino-acids. These provide the scaffolding of plants, and their energy stores. Animals exploit these by breaking them down to their building blocks and then reconstructing them, as we do, to glycogen and proteins.

In the proteins there is a 'language' produced by 'letters', the amino acids. This body language makes our hair, bones, blood, muscles and brains. Perhaps most magically of all, it makes the enzymes that control our body chemistry.

Our structure and activity is controlled by proteins. How are these assembled and where is the plan for each of their structures? The construction code is held - one for each amino acid in 3 letter segments - by our final handed giant, DNA, present in the nuclei of all our cells. We are complicated structures and the enormous coded messages must be handed on to our descendants. If the code is interfered with, the result is cancer. The chemist leads in the fight against this disease with weapons which recognise and destroy the DNA of the rogue cells. For each of us, our DNA contains the blueprint for the construction of our brains, which in turn control our language and our handedness, so we now see that language and handedness are the result of chemical events dependent on molecular chirality.

We must never suppose that we know everything. A final mystery - where did handed molecules come from in the first place?


Natural world


BBC / Royal Institution




Charles Stirling



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