Photosynthesis Earth's atmosphere, and supplies all of the organic compounds and most of the energy necessary for life on Earth. Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centres that contain green chlorophyll pigments. In plants, these proteins are held inside organelles called chloroplasts, which are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane. In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. The hydrogen freed by the splitting
Bacterial cell structure different bodies of water. Deep lakes that experience winter mixing expose the cells to the hydrostatic pressure generated by the full water column. This will select for species with narrower, stronger gas vesicles. The cell achieves its height in the water column by synthesising gas vesicles. As the cell rises up, it is able to increase its carbohydrate load through increased photosynthesis. Too high and the cell will suffer photobleaching and possible death, however, the carbohydrate produced during photosynthesis increases the cell's density, causing it to sink. The daily cycle of carbohydrate build-up from photosynthesis and carbohydrate catabolism during dark