Chemistry and life / by Sir Frederick Gowland Hopkins.

  • Frederick Hopkins
Date:
1933
Catalogue details

Licence: Public Domain Mark

Credit: Chemistry and life / by Sir Frederick Gowland Hopkins. Source: Wellcome Collection.

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    deal with inorganic materials alone. They obtain their energy by oxidising various inorganic materials: hydrogen, sulphur, iron, ammonia or nitrites. Provided with such energy, they carry out the remarkable syntheses which lead to their growth and start by rivalling the green plant in the endothermic reduction of CQg, though without the aid of solar energy. Such organisms are of the greatest interest, because their activities seem to carry us nearer than those of other organisms to the beginnings of life; perhaps to the days before evolution had established the chloro- phyll function of the green plant, that great success of Nature. These autotrophic bacteria suffer however from the very low efficiency which characterises their method of obtaining energy, and it would seem as though they are the survivors from an unsuccessful evolutionary effort. Because of the interest which cannot but be felt in all the chemical adjustments which are associated with the steps and stages in the evolution of living forms, I will close by calling your attention to a group of auto- trophic bacteria recently studied which have gone a step farther than others towards success in obtaining cheaper energy. I allude to the purple sulphur bacteria, a group which still relies upon the oxidation of sulphur, but which, having developed an adequate pigment for the purpose, can trap and employ radiant energy as well. A careful study of their metabolism has shown that the following reaction represents the process by which the. preliminary reduction of CO, to formic aldehyde occurs. But these particular organisms require sunlight for growth because the reaction represents a photosynthetic process. H,S + 2H,O + 2CO, = 2CH,O + H,SO, Speaking in parables, we may say that Nature has made many experiments, some successful and others unsuccessful, in develop- ing the forms of living organisms; while in relation with these she has made many chemical experiments also with varying success. In biology, success means nice adjustment between the equipment of an organism and the opportunities its environment provides. Influenced perhaps by the title chosen for my lecture I have dealt with matters which seem remote from practice, though they may be nearer to it than we think. I might perhaps have dealt rather with the practical applications of biochemistry which are becoming numerous enough. I would indeed advise any young chemist when deciding upon a career to bear their
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