MICRB265 Lecture Notes - Green Sulfur Bacteria, Purple Bacteria, Light-Dependent Reactions
Document Summary
Sulfur granules in sulfur bacteria act as e- storage. Atp is still synthesized via atpase in the cytoplasmic membrane just like other bacteria. Both purple nonsulfur and green sulfur bacteria implement cyclic electron flow: electrons leave cycle to produce nadh. Purple nonsulfur have to do reverse electron flow in order to do this. In green sulfur bacteria, the electrons are boosted to a higher reduction potential (excited by a shorter wavelength) which will allow them to reduce nad+ directly and without the need for reverse electron flow. Photosynthesis in plants is essentially a combination of purple non-sulfur bacteria and green sulfur bacteria"s reaction centers: equivalent to the two photosystems found in photosynthesizing plant cells. Creates o2; electrons are from lysed water. Water is so readily available that usually, cyclic e- flow is not necessary. If water levels are low, then the plant cells will have to resort to cyclic e- flow since water is the electron donor.