|FABER & FABER|
the observer Sat 02 May 2009
"Perhaps our eyes need to be washed by our tears once in a while, so that we can see life with a clearer view again," Alex Tan once claimed. That is just the half of it. When we cry, we do a lot more than just clear up our vision. We improve our health. Tears, it transpires, help us fight infection. They contain lysozyme, a chemical that can cleave the sugar chains in the walls of invading bacteria. Thus washed with tears, a bacterium simply bursts open and dies. So yes, a good cry certainly has its advantages.
Lysozyme, we should note, is just one of the thousands of chemical workhorses whose combined efforts keep our cells healthy and active, a set of observations that takes us to the core of this intriguing examination of the basic unit of life: the cell. These tiny entities - named from the Latin, cella, for small rooms - are, quite simply, "the most complex objects in the universe", according to Lewis Wolpert.
And given that all living things on our planet are made of cells, any attempt to understand how and why we live and die obliges us to study cells, their components and the forces that maintain and destroy them, argues Wolpert. As he says: "It is only from cells that we can find out what life is."
Cells cover us in skin, carry nerve impulses, absorb food, fight infections and move oxygen around our arteries. Each of us has around 200 different types of cell in our bodies. Yet despite their diverse functions, all cells are similar. Each is, in effect, a ball of "watery salt" that contains a nucleus that holds two metres of genetic material. This, in turn, directs the manufacture of proteins from which new cells are made.
In addition, a cell is covered with a delicate membrane that carefully controls what passes in and out of it; possesses tiny power packs, called mitochondria; exploits chemical scissors called enzymes to assemble complex chemicals or to split them up (as lysozyme does); and uses microscopic pumps to keep concentrations of sodium and potassium ions at their correct levels.
For good measure, all this highly sophisticated machinery operates at an extraordinary rate. Enzymes act on about 1,000 molecules a second. Thus we can think of ourselves as collections of cellular sweatshops in constant, feverish operation. Two million red blood cells, which carry life-sustaining oxygen around our bodies, are manufactured every second in our bone marrow while billions of nerve impulses constantly travel through billions of the nerve cells inside our brains. Even on the outside, there is plenty of activity: the outer layers of our skin are replaced a thousand times during a normal lifetime, for example.
Yet, as Wolpert notes, all these cells in our bodies - and in the bodies of all other creatures - operate independently. "There is no overall controller of this cellular society: it is a true co-operative," he says.
And this is one of the most extraordinary features about life on Earth: its individual members are composed of units whose assemblage arose through blind chance and which operate without any central control. (Our brains have limited control over only a few cells, such as muscle, and no influence at all over skin growth, liver function or heartbeat.) For Wolpert, a civil engineer turned biologist, that functioning is simply "miraculous". Thus he has devoted his professional life to an object of such sophistication that it "almost always turns out to exceed one's expectations".
And, by and large, he has done his tiny charges justice in this sparsely written, succinctly argued work. There are no florid touches or biographical interludes in this narrative, just straightforward accounts of cells in action. The overall impact is perhaps a little too dry for my liking. On the other hand, Wolpert has had the sense to tell a good story with minimum fuss and allow nothing to divert attention from what he believes is the greatest wonder of our world: the living cell.
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