Photosynthetic Megacomplex (image) Washington University in St. Louis Caption The photosynthetic megacomplex from a cyanobacterium, which scientists have managed to isolate in its complete, functioning form, weighs about 6 million Daltons. It has three parts: on top is a light-harvesting antenna complex called a phycobilisome that captures and funnels the energy in sunlight to two reaction centers, Photosystem II (the complex protruding beneath the antenna) and Photosystem I (the complexes to either side Photosystem II). The megacomplex is embedded in a membrane shown as a green carpet. Click the image above for a larger version. Credit Haijun Liu Usage Restrictions please credit Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.