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   ◄ You are here

3.1 (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.