THE CHEMISTRY OF LIFE

Steven Rose with Sarah Bullock

Penguin, London, 1991.


Anyone wishing to learn more about the molecular detail of how organisms work can do no better than to start with this book. Although there are chemical formulae throughout the text, there is no requirement to be a chemist to follow the plot. A very enthralling plot it is too, with glimpses of the immense possibilities in biochemistry, where the same chemical substance may exist in more than one form, or isomer, as in considerations like this:

"Synge, one of the inventors of chromatography as a method of separation and purification, calculated that for a relatively modest protein - with a molecular weight of 34 000, and with 288 amino acids, but made up of only 12 different amino acids out of the possible 20 - the number of isomers is 10300. If only one molecule of each isomer were to exist, the total mass would be some 10280 grams. As the weight of the earth is only 1027 grams, it is very clear that only a tiny fraction of these isomers in fact exist." (p.61)

How energy is acquired and used by living beings is discussed at various levels throughout the book, as in this description of the photosynthetic pigment, chlorophyll:

"The ring structures contain a series of alternating double and single bonds, and the absorption of a given small amount of light (a quantum) of a particular wavelength causes a sort of vibration, or resonance around these bonds. Because of the close packing and stable orientation of the pigment molecules... this resonance energy can be transferred from one pigment molecule to another until it is eventually channelled into a slightly different cholorophyll molecule from which it cannot escape." (p.353)

This is what it is to really discuss energy in the organism, and to study the relationships between life and chemistry and physics.

"This is not to say that life reduces to 'mere' chemistry and physics. There are biological principles which express the organizing relationships between macromolecules, cells, and organisms, and which must include within them an understanding of historicity... Such principles, however, are materialist; to understand the existence and origins of life, and of humans, needs no recourse to principles outside those of the material world." (p.365)


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BIOLOGY



Paul Taylor 2001