The Anatomy of Chloroplasts

In plants, photosynthesis primarily takes place within the leaf's dense mesophyll cell layers because they contain the highest number of chloroplasts.

Chloroplasts are specialized double membrane organelles that enclose an aqueous cavity called the stroma.

Inside the stroma, lie membranous sacs called the thylakoids that are layered on top of each other to form multiple stacks called the grana.

The grana are interconnected with single thylakoids called the stroma thylakoids.

Embedded within the thylakoid membranes are multiprotein complexes such as the photosystems.

Photosystems contain the antenna proteins bound to numerous pigment molecules, like chlorophylls, which help them absorb light and initiate the first stage of light-dependent reactions.

Meanwhile, the second stage, the Calvin cycle, takes place in the stroma.

With both processes working together, plants are able to produce their own food, thanks to the biochemical factories found in the chloroplast.