Grana and stroma are both parts of chloroplasts, the organelles responsible for photosynthesis in plant cells. They have distinct structures and functions:
Grana
- Structure: Grana (singular: granum) are stacks of flattened, sac-like structures called thylakoids. These thylakoids are arranged like stacks of pancakes. Think of them as the solar panels of the chloroplast.
- Function: The grana are the sites where the light-dependent reactions of photosynthesis occur. This is where chlorophyll, the pigment that captures light energy, is located.
Stroma
- Structure: The stroma is a fluid-filled space surrounding the grana. It's the thick, jelly-like matrix filling the chloroplast. Think of it as the "factory floor" where the products are assembled.
- Function: The stroma is the location of the light-independent reactions (also known as the Calvin cycle) of photosynthesis. This is where carbon dioxide is converted into sugars using the energy produced during the light-dependent reactions. The stroma also contains enzymes and other molecules needed for these reactions.
In short: Grana capture light energy, while the stroma uses that energy to make sugars. They work together in a coordinated process to carry out photosynthesis. The references consistently support this distinction.
