Grana

Grana are structures within chloroplasts consisting of stacks of flat, membrane structures (thylakoids). Grana appear as if they were stacks of coins inside the chloroplasts (Figure 17.4c).

The interior membrane layers of the grana are rich in photosystem II; by contrast, the stroma lamellae (structures that connect grana) are rich in photosystem I (Figure 17.16).

See also: Chloroplast Anatomy, Stroma, Thylakoid Membrane, The Chloroplast, Thylakoid Lumen, Photosystem II, Photosystem I, Figure 17.12