1.6: Chloroplasts

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Chloroplasts are large organelles and their function is the formation and storage of carbohydrates from photosynthesis. The chloroplast is bounded by a double membrane.

The matrix of the chloroplast is known as the stroma. Also inside the chloroplast are separate internal membranes that form lamellae or rounded tongue-like thylakoids within the enclosing double membrane. These tongue-like or disk-like thylakoid membranes may be stacked in layers and these are referred to as grana. Grana are joined to each other by other membranes.

Chloroplasts in the leaf cell of a moss, Plagiomnium affine. — Figure 1.14. Chloroplasts in the leaf cell of a moss, *Plagiomnium affine*. (Image: Kristian Peters, CC 3.0 attribute, share alike)

Figure 1.15. Internal membrane structure within a chloroplast. (Kelvinsong CC BY-SA 3.0).

There are a range of other organelles which are similar to chloroplasts that are used for storage and pigmentation.

Figure 1.16. Other plastids in a plant cell. Chromoplasts contain colour pigments, whereas other plastids are used for storage. (By Mariana Ruiz Villarreal LadyofHats, Public Domain).