Chloroplast

Most living cells of so-called higher plants contain a number of tokens of a type of plastid called chloroplasts, tiny, somewhat football-shaped, bacteria-sized organelles, a few micrometers in size, up to several hundred in number in the green cells, each a separate compartment whose boundary consists of two membranes, the interior of the inner membrane of which contains a semiliquid matrix suspending a system of membranes, called thylakoids, whose membranes embed molecules of chlorophyll and other pigments that absorb energy from sunlight, initiating the physico-chemical process of photosynthesis.

Algae, mostly single-celled members of the plant kingdom, and diatoms, among the protists, a mixed group of mostly single-celled eukyotic organisms that do not fall under the eukaryotic kingdoms of plants, fungi and animals, also contain chloroplasts and carry out photosynthesis.