Grana are stacks of thylakoid membranes inside chloroplasts. Each granum is a column of tightly stacked, disk-shaped thylakoids, and grana are interconnected by stromal (intergranal) thylakoids that extend through the stroma to link different granum stacks. Key points:
- Structure: Thylakoid membranes form organized, parallel stacks—grana—with narrow lumen spaces between the membranes. These stacks are the primary sites of the light-dependent reactions of photosynthesis.
- Connectivity: Grana are connected by stromal thylakoids, creating a continuous network within the chloroplast.
- Function: The tight packing increases surface area for light capture and electron transport while maintaining organized access to photosystems and components.
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