Photosynthesis

ISBN-13: 9789401066624 / Angielski / Miękka / 2013 / 160 str.

R.P. Gregory

Opis

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."

Spis treści

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.- 2.1.1 Membrane lipids.- 2.1.2 Membrane proteins.- 2.2 The membranes of chloroplasts and photosynthetic bacteria.- 2.3 Pigments.- 2.3.1 Spectroscopy.- 2.3.2 Chlorophylls, phycobilins and carotenoids.- 2.4 Pigment-protein complexes.- 2.5 Antenna complexes.- 2.5.1 Chlorosomes.- 2.5.2 Phycobilisomes.- 2.5.3 The antenna of the purple bacteria.- 2.5.4 Complexes in the green plant chloroplast.- 2.6 Reaction-centre complexes.- 2.6.1 Green plants possess two types of photosystem.- 2.6.2 Purple bacteria possess the simplest reaction centre.- 2.6.3 Green plants: PSII resembles purple bacteria.- 2.6.4 Green plants: PSI—more chlorophyll attached to fewer proteins.- 2.6.5 Green sulphur bacteria.- 2.6.6 Heliobacterrium chlorum.- 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.- 3.2.1 Fluorescence.- 3.2.2 Excitation energy transfer.- 3.2.3 Radiationless deactivation.- 3.3 Antenna chlorophylls in chloroplasts.- 3.3.1 PSI.- 3.3.2 PSII.- 3.3.3 Excitation migration.- 3.3.4 Variables affecting the fluorescence yield.- 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.- 4.1.1 Cytochromes.- 4.1.2 Chlorophyll.- 4.2 Quinones—the electron acceptors for the reaction centre of PSII in green plants and purple bacteria.- 4.2.1 Fluorescence induction.- 4.3 Ferredoxins—the electron acceptors in the reaction centres of green plant PSI and green sulphur bacteria.- 4.3.1 Electron transport within PSI.- 4.3.2 Ferredoxin is the diffusible electron acceptor.- 4.3.3 The RC of green sulphur bacteria resembles PSI of green plants.- 4.4 Electron donors.- 4.4.1 Four families of C-cytochromes.- 4.4.2 Purple bacteria.- 4.4.3 Water is the ultimate electron donor to PSII in green plants.- 4.4.4 Plastocyanin is the electron donor to PSI in green plants.- 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.- 5.2.1 Purple bacteria.- 5.2.2 Chloroplasts.- 5.2.3 Green sulphur bacteria.- 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.- 6.4.1 How much energy is required for ATP synthesis?.- 6.4.2 The ATP synthase or F-ATPase.- 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.- 7.2.1 The reductive citrate cycle.- 7.2.2 The reductive pentose cycle.- 7.2.3 Photorespiration.- 7.2.4 C4 photosynthesis.- 7.2.5 Chloroplasts and respiration.- 7.3 Chloroplast-cytoplasm transport.- 7.3.1 The products of photosynthesis: starch and sucrose.- 7.3.2 Guard cells.- 7.3.3 Carbon dioxide accumulation.- 7.4 Molecular cell biology.- 7.4.1 Genes exist in the cell nucleus and in organelles.- 7.4.2 The control of chloroplast synthesis.- References and Further Reading.