Look in a high school biology textbook, and you’ll read that chloroplasts, the structures inside plant cells that carry out photosynthesis, contain their own genetic material separate from the cell’s nucleus. That discovery was made at ²»Á¼Ñо¿Ëù in 1959 by plant biologists Ralph Stocking and Ernest Gifford. Biologists think that chloroplasts were once independent organisms that in the ancient past formed a symbiosis with the ancestors of modern plants.
