Chloroplasts are organelles in plant and algae cells that have a double membrane and a third internal membrane system. They are oval-shaped and contain chlorophyll, a green pigment that absorbs light for photosynthesis.

Structure

• Outer membrane: The external surface of the chloroplast
• Inner membrane: Located beneath the outer membrane
• Intermembrane: A thin layer between the inner and outer membranes
• Stroma: The space within the inner membrane that contains DNA and ribosomes
• Thylakoid membrane: An internal membrane system that forms a network of flattened discs called thylakoids
• Grana: Stacks of thylakoids

Function

1. Photosynthesis: The process of converting carbon dioxide and water into glucose and oxygen using sunlight
2. Energy storage: The storage of energy in the form of carbohydrates