Chloroplast

In all autotrophic eukaryotes, photosynthesis takes place inside an organelle called a **chloroplast**. For plants, chloroplast containing cells exist in the mesophyll. Chloroplasts have a double membrane envelope (composed of an outer membrane and an inner membrane). Within the chloroplast are stacked, disc-shaped structures called thylakoids. Embedded in the thylakoid membrane is chlorophyll, a pigment (molecule that absorbs light) responsible for the initial interaction between light and plant material, and numerous proteins that make up the electron transport chain. The thylakoid membrane encloses an internal space called the thylakoid lumen. A stack of thylakoids is called a granum, and the liquid-filled space surrounding the granum is called stroma or “bed” (not to be confused with stoma or “mouth,” an opening on the leaf epidermis).



*LICENSES AND ATTRIBUTIONS CC licensed content, Shared previously, Overview of Photosynthesis, Authored by: OpenStax College. License: CC BY: Attribution. License Terms: Download for free at https://cnx.org/contents/GFy_h8cu@9.36:W7ctJeSI@8/Overview-of-Photosynthesis.*