Tomato chloroplast. Coloured transmission electron micrograph (TEM) of a section through a chloroplast from a tomato plant (Lycopersicon esculentum). Chloroplasts are organelles found in some plant cells. They are the site of photosynthesis in the cell. Photosynthesis is the process by which plants turn carbon dioxide into sugars using sunlight. The chloroplasts contain numerous parallel membranes (grana, dark, running from upper left to lower right) containing the green pigment chlorophyll. Starch granules (orange) are seen in this chloroplast. Magnification: x25,000 at 5x7cm size. x30,000 at 6x9cm