A pigmented lamellar or vesicular structure that can be isolated from disrupted photosynthetic bacteria or blue-green algae. These organisms have no chloroplasts. Their plasma membrane may be projected in folds into the cytoplasm (see lomasome
) forming lamellae that have, therefore, double unit-membrane structure. The pigments and most of the enzymes required for the light-induced electron transport and phosphorylation processes of photosynthesis, are located in the plasma membrane and lamellae. The principle photosynthetic pigment in the blue-green algae is chlorophyll a; in purple bacteria, bacteriochlorophyll a or d; and in green bacteria, bacteriochlorophyll b or c.