Photosynthesis chloroplastic membrane

Chloroplasts are the site of photosynthesis, the reactions by which light energy is converted to metabolically useful chemical energy in the form of ATP. These reactions occur on the thylakoid membranes. The formation of carbohydrate from CO9 takes place in the stroma. Oxygen is evolved during photosynthesis. Chloroplasts are the primary source of energy in the light. 

Powles, S.B. Bjorkman, O. (19826). Photoinhibition of photosynthesis effect on chlorophyll fluorescence at 77 K in intact leaves and chloroplast membranes of Nerium oleander. Planta, 156, 97-107. 

The individual steps of the multistep chemical reduction of COj with the aid of NADPHj require an energy supply. This supply is secured by participation of ATP molecules in these steps. The chloroplasts of plants contain few mitochondria. Hence, the ATP molecules are formed in plants not by oxidative phosphorylation of ADP but by a phosphorylation reaction coupled with the individual steps of the photosynthesis reaction, particularly with the steps in the transition from PSII to PSI. The mechanism of ATP synthesis evidently is similar to the electrochemical mechanism involved in their formation by oxidative phosphorylation owing to concentration gradients of the hydrogen ions between the two sides of internal chloroplast membranes, a certain membrane potential develops on account of which the ATP can be synthesized from ADP. Three molecules of ATP are involved in the reaction per molecule of COj. 

Photosynthesis occurs in the plant cell organelle called the chloroplast. During the process of photosynthesis, electrons are transferred from H20 to NADP+ via an electron carrier system. The energy released by electron transport is converted into the form of a proton gradient and coupled to ADP phosphorylation. In this experiment a method is introduced to demonstrate the formation of the proton gradient across the chloroplast membranes. 

When electrons flow from photosystem I to photosystem II, protons are transported across the chloroplast membranes as indicated in Figure E9.1. This aspect of photosynthesis will be discussed in a later section. 

Kyle DJ (1987) The biochemical basis for photoinhibition of Photosystem II. In Kyle DJ, Osmond CB and Arntzen CJ (eds) Photoinhibition. Photoinhibition, Topics of Photosynthesis, pp 197-226. Elsevier, Scientific Press, Amsterdam KyleDJ, Ohad I and Arntzen CJ (1985) Molecular mechanisms of compensation to light stress in chloroplast membranes. In Key JL and Kosuge T (eds) Cellular and Molecular Biology of Plant Stress, pp 51-69. Liss, New York Laisk A, Oja V, Rasulov B, Eichelmann H and Sumberg A (1997) Quantum yields and rate constants of photochemical and non-photochemical excitation quenching—Experiment and model. Plant Physiol 115 803-815 Lancaster CRD and Michel H (1996) Three-dimensional stmetures... 

The chloroplast, a plant organelle, is the site of photosynthesis in higher plants and algae. Like mitochondria, chloroplasts carry their own DNA to code for some of their proteins, as well as the ribosomes necessary for translation of the appropriate mRNAs. Chloroplasts may have evolved from cyanobacteria, which have membrane structures like chloroplast membranes. 

Interferences of Photosynthesis Inhibitors with a Common Chloroplastic Membrane Protein... 

It is obvious now since the pioneering work of Wintermans (1960) that galactolipids in plants having the Calvin-Benson pathway of photosynthesis (Cs plants) or the C4 dicarboxylic pathway of photosynthesis (C4 plants) appear to be concentrated within the chloroplast membranes (Lichtenthaler and Park, 1963 Nichols, 1963 Allen et al., 1966a,b Appelqvist et al.. 

Since it is found in the chloroplast membranes of all higher plants, trans-16 1 has been thought to play an important role in some aspect of photosynthesis (reviewed in Dubacq and Tremolieres, 1983). The availability of a mutant line provided an excellent opportunity to test the various proposed roles. Therefore, we compared the mutant and the wild type by a number of criteria with the following results ... 

The effects of the fadP mutation on photosynthesis have been examined in some detail. Our preliminary results indicate that the mutation has no apparent effect on the growth rate or the rate of photosynthesis (expressed on a chlorophyll basis) at any temperature in the range of 10 C to 30°C (McCourt et al., 1986). The mutation also has no effect on the fluorescence characteristics and has only a slight effect on membrane fluidity as measured by fluorescence polarization studies. Measurements of temperature-induced fluorescence yield enhancement also failed to reveal a difference between the mutant and the wild-type. Thus, we have been unable to detect major effects on the functional properties of chloroplast membranes associated with a major reduction in trlenolc acids. This conclusion contrasts somewhat with the interpretation of other studies in which.the amount of chloroplast membrane unsaturation was reduced by growth in chemical inhibitors (Laskay and Lehoczki, 1986 Leech et al., 1985) or by catalytic hydrogenation (Thomas et al., 1986). Therefore, we consider it possible that the effects of these experimental treatments may be due to non-specific effects. 

The photosynthetic apparatus in green plants and algae is located in the chloroplast, which is a flattened, double-membraned structure about 150-200 A thick/4,5 The two flat membranes lie one above the other and are united at their peripheries. These double-membraned structures have been termed thylakoids (from the Greek sacklike )/ Each membrane of the thylakoid consists of a water-insoluble lipoprotein complex which contains the light-absorbing chlorophyll and other pigments utilized in photosynthesis. 

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