Chloroplasts have two primary functions:
- Photosytem energy capture and conversion: They are the site of photosynthesis, where light energy is captured by chlorophyll and other pigments and converted into chemical energy (ATP and NADPH) to drive the synthesis of sugars from carbon dioxide and water.
- Carbon fixation and carbohydrate production: Using the ATP and NADPH from the light reactions, the Calvin cycle fixes CO2 into organic sugars (like glyceraldehyde-3-phosphate), which are ultimately used to build starches and other carbohydrates for the plant.
Contextual note:
- In addition to these main roles, chloroplasts engage in other important activities such as amino acid and fatty acid synthesis, pigment production, and reactive oxygen species management, but photosynthesis and carbohydrate biosynthesis are the central, defining functions.
