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Photosynthesis--the capture of light energy by living organisms -is a simple enough concept, but its investigation draws on the resources of disciplines from all fields of science. The aim of this text is to provide a clear, stimulating and essentially affordable coverage for undergraduate students of biology. The activity of science is debate and practical experiment; its product is a body of propositions which at any given time reflects the judgment and prejudices of those taking part. The value of a proposition is related to the conceivable alternatives, and writing it down without its context creates the false impression that science progresses by compilation of an increasing list of absolute truths. It does not; the facts and figures pres ented in the following pages have no intrinsic value unless they can be used by the reader to support an argument or point of view. In short, the reader is urged to respond 'So what?' to every item. Secondly, ideas-like other foods-should be date-stamped; science is inseparable from its history. I have set out time-charts to represent the evolution of our understanding in certain areas. I have assumed that the reader is pursuing a course with a content of biochemistry, microbiology and plant science, or has access to basic texts. I have assumed also that common methods such as spectrophotometry, chromatography and electrophoresis, as well as the techniques of mol ecular biology, will be either part of the same course or in active use nearby.
Sommario
1 Photosynthesis The capture of light energy by living organisms.- 1.1 Photosynthesis in historical context.- 1.2 Photosynthesis in a comparative context.- 2 The Organisation of Photosynthetic Structures.- 2.1 Biological membranes.- 2.2 The membranes of chloroplasts and photosynthetic bacteria.- 2.3 Pigments.- 2.4 Pigment-protein complexes.- 2.5 Antenna complexes.- 2.6 Reaction-centre complexes.- 2.7 Summary.- 3 Primary Photophysics Times from 1 fs to 100 ps.- 3.1 Light absorption: formation of excited states of molecules.- 3.2 Possible fates of excited states.- 3.3 Antenna chlorophylls in chloroplasts.- 3.4 Photochemical charge separation in reaction centres.- 4 Electron Transfer Within Reaction-Centre Complexes Times from 4 ps to 0.15 ms.- 4.1 Redox potentials.- 4.2 Quinones-the electron acceptors for the reaction centre of PSII in green plants and purple bacteria.- 4.3 Ferredoxins-the electron acceptors in the reaction centres of green plant PSI and green sulphur bacteria.- 4.4 Electron donors.- 4.5 Summary.- 5 Electron Transport by Diffusible Molecules Times from 1 ms to 20 ms.- 5.1 The ubiquitous cytochrome bc complex: the quinol cytochrome c reductase.- 5.2 Patterns of electron transport: cyclic or non-cyclic.- 5.3 Summary.- 6 The Production of ATP Times from 1 s to 100 s.- 6.1 Electron transport generates an H + -ion gradient.- 6.2 A proton gradient has both electric and pH components.- 6.3 How much work can be stored by the proton gradient?.- 6.4 The proton gradient drives ATP formation.- 6.5 The PMF controls the rate of electron transport.- 6.6 Reverse electron transport.- 7 Metabolic Processes and Physiological Adjustments Seconds to hours.- 7.1 Ferredoxin-dependent reactions.- 7.2 Carbon dioxide fixation.- 7.3 Chloroplast-cytoplasm transport.- 7.4Molecular cell biology.- References and Further Reading.
