Chloroplasts

Endosymbiotic origin of chloroplasts

Chloroplasts are one of many types of organelles in photosynthetic eukaryotic cells. They evolved from cyanobacteria through a process called organellogenesis. Cyanobacteria are a diverse phylum of gram-negativebacteria capable of carrying out oxygenic photosynthesis. Like chloroplasts, they have thylakoids. The thylakoid membranes contain photosynthetic pigments, including chlorophyll a. This origin of chloroplasts was first suggested by the Russian biologist Konstantin Mereschkowski in 1905 after Andreas Franz Wilhelm Schimper observed in 1883 that chloroplasts closely resemble cyanobacteria. Chloroplasts are only found in plants, algae, and some species of the amoeboidPaulinella.