A chloroplast is a double-membrane organelle present in the cells of plants and algae, responsible for photosynthesis. It is green in color due to the presence of the pigment chlorophyll, which captures light energy. Chloroplasts are generally oval-shaped and have an inner fluid-like matrix called the stroma. Within the stroma, there are numerous membranous sacs called thylakoids, which are stacked together to form grana. This is where the light-dependent reactions of photosynthesis occur. Chloroplasts also contain their own DNA and ribosomes, allowing them to synthesize some of their own proteins. They are involved in the production of glucose and oxygen from carbon dioxide and water in the presence of sunlight.
