The site of photosynthesis

Although, leaves are the main sites of photosynthesis in most plants, it can take place in any part that is green. These green parts have chloroplasts,which contain all the biochemical machinery necessary for the light-dependent and light-independent stages of photosynthesis.

Chloroplasts act as compartments, isolating the photosynthetic reactions from other cellular activities. Each chloroplast consists of two membranes enclosing a gelatinous matrix called the stroma. The stroma contains ribosomes, circular DNA, and enzymes used in photosynthesis. Suspended in the stroma are thylakoids. These are disk-like membrane sacs, several of which are stacked in a group to form a granum (plural grana). The space inside each thylakoid in a stack is connected with the other thylakoids in the stack, forming a continuous fluid-filled compartment called the thylakoid space. The thylakoid membranes contain photosynthetic pigments, including chlorophyll.

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