Chloroplasts

Semi-autonomous units in the cells of green plants; site of photosynthesis

Chloroplasts are a type of plastid (sub-cellular organelle) that only occur in plant cells exposed to light.

Photosynthesis takes place inside of chloroplasts. By means of this essential metabolic process of green plants, light energy is transformed into chemical energy in the form of carbohydrates. Chloroplasts are able to move inside the cell in response to light conditions; in weak illumination, they arrange themselves so as to capture as much light as possible, but when the light incidence is strong, they turn on end to minimise exposure. Chloroplasts have their own genetic system consisting of DNA, RNA and ribosomes to produce some of their own proteins.