Chloroplasts
The site of photosynthesis is the chloroplast, a membranous subcellular organelle. Chloroplasts vary considerably in size and shape but are typically 5 m long ellipsoids. Like a mitochondrion, it contains an inner membrane and an outer membrane with an intervening membrane. The inner membrane surrounds a stroma containing soluble enzymes and membranous structures called thylakoids, which are flattened sacs. A pile of these sacs is called a granum. Regions of thylakoid membrane called stroma lamellae connect different grana. The thylakoid membranes separate the thylakoid space from the stroma space.

The photosynthetic pigments and all the enzymes required for the primary light reactions are embedded in the thylakoid membranes. The fluid in the stroma contains most of the enzymes required for the carbon fixation reactions.

Biochemistry (for Agricultural Sciences) By B. Thayumanavan, Page no: 183.