A plastid containing chlorophyll, developed only in cells exposed to the light. Chloroplasts are minute flattened granules, usually occurring in great numbers in the cytoplasm near the cell wall, and consist of a colorless ground substance saturated with chlorophyll pigments. Under light of varying intensity they exhibit phototactic movements. In animals chloroplasts occur only in certain low forms.

A double-membrane-bound organelle that contains chlorophyll and is found in plant cells. Chloroplasts are responsible for mediating photosynthesis.

In African Violets and other plants, the part of a plant cell which contains chlorophyll. A typical leaf cell contains about 50 chloroplasts.

Membrane-bound organelle found in the cytoplasm of various eukaryotic organisms that contain the chlorophyll pigments and the enzyme systems for photosynthesis. Prokaryotic photosynthetic organisms do not have chloroplasts.