photosynthesis
Chloroplasts Like the mitochondria, chloroplasts have their own DNA and ribosomes, but chloroplasts have an entirely different function. Chloroplasts are plant cell organelles that carry out photosynthesis. Photosynthesis is the series of reactions that use carbon dioxide, water, and light energy to make glucose and oxygen. This is a major difference between plants and animals; plants autotrophs are able to make their own food, like sugars, while animals heterotrophs must ingest their food. Like mitochondria, chloroplasts have outer and inner membranes, but within the space enclosed by a chloroplasts inner membrane is a set of interconnected and stacked fluid-filled membrane sacs called thylakoids Figure 4.17 . Each stack of thylakoids is called a granum plural = grana . The fluid enclosed by the inner membrane that surrounds the grana is called the stroma.