Thylakoid

Cell biology
Chloroplast
Components of a typical chloroplast 1 Granum 2 Chloroplast envelope 2.1 Outer membrane 2.2 Intermembrane space 2.3 Inner membrane 3 Thylakoid   ◄ You are here 3.1 Thylakoid space (lumen) 3.2 Thylakoid membrane 4 Stromal thylakoid 5 Stroma 6 Nucleoid (DNA ring) 7 Ribosome 8 Plastoglobulus 9 Starch granule

Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana (singular: granum). Grana are connected by intergranal or stromal thylakoids, which join granum stacks together as a single functional compartment.

In thylakoid membranes, chlorophyll pigments are found in packets called quantasomes. Each quantasome contains 230 to 250 chlorophyll molecules.