The chloroplast is an organelle found only in plant cells. The function of the chloroplast is to make energy for the cell using water, energy from the sunlight and carbon dioxide. The process of making this energy is called photosynthesis. Photosynthesis happens in the chloroplast. The type of energy made by photosynthesis in the chloroplast is a sugar called glucose. That glucose is then broken down into ATP. Chloroplasts are green in color due to the chemical chlorophyll that is present in the chloroplast. Thylakoid stacks can be found inside the chloroplast. These stacks have chlorophyll on their surface which allows photosynthesis to happen.