Harvesting light energy

Rebel I, Subramanian V, Kuno M, Kamat PV (2006) Quantum dot solar ceUs. Harvesting light energy with CdSe nanocrystals molecularly linked to mesoscopic HO2 films. J Am Chem Soc 128 2385-2393... 

Known function Image- and non-image forming light detection Photoisomerase, harvesting light energy to convert all-retinal to retinal Unknown... 

The Role of Mitochondria in Apoptosis and Oxidative Stress Photosynthesis Harvesting Light Energy... 

Photoconductivity forms the basis for photocopying, and photovoltaic effects form the basis for solar cells being developed to harvest light energy. 

Chlorophyll is the dominant molecule for light harvesting in biology. Moreover, the special pair of chlorophyll molecules in the reaction centre not only harvests light energy but also provides the first step of energy transduction. At this centre the photon generates a biradical responsible for electron flow, which results in the first membrane potential [1],... 

Chemists are studying the structure and kinetics of the photosynthetic reaction center both to understand the fundamentals of this important natural process and to design new materials that mimic nature s ability to harvest light energy at such high efficiency. Artificial photosynthesis may lead to carbon-based materials that will replace the silicon collectors in solar cells in the 21st century. This will help reduce human dependence on stored fossil fuels as energy sources in the future. 

The uptake of nitrate and subsequent conversion to reduced nitrogen in cells requires a change of five in the oxidation state and proceeds in a stepwise fashion. The initial reduction takes place via the nitrate/nitrite reductase enzyme present in phytoplankton and requires large amounts of the reduced nicotinamide-adenine dinucleotide phosphate (NADPH) and of adenosine triphosphate (ATP) and thus of harvested light energy from photosystem II. Both the nitrogenase enzyme and the nitrate reductase enzyme require iron as a cofactor and are thus sensitive to iron availability. 

In modified porphyrins such as chlorophylls, this oxidation can be driven by the absorption of solar energy. Chlorophylls harvest light energy and channel it for use in photosynthesis. Chlorophylls are closely related to porphyrins. In the case of chlorophyll, however, the metal is magnesium and the ligand includes a reduced and modified porphyrin. In photohsystems I and II, chlorophylls form weak dimers, which is one way plants control absorption of the proper solar radiation. The chlorophyll shown in Fig. 5 contains a long alkane chain that helps it associate with the membrane within a chloroplast. 

---