Photosynthesis in plants primarily takes place inside the chloroplasts, which are specialized organelles found in the mesophyll cells of leaves. The mesophyll is the middle layer of the leaf where most photosynthesis occurs
. Within the chloroplasts, photosynthesis happens in two main parts:
- Light-dependent reactions occur in the thylakoid membranes (stacked into structures called grana). Chlorophyll pigments in these membranes absorb light energy to produce ATP and NADPH, while splitting water molecules and releasing oxygen as a byproduct
- Light-independent reactions (Calvin cycle) take place in the stroma, the fluid surrounding the thylakoids inside the chloroplast. Here, ATP and NADPH are used to convert carbon dioxide into glucose and other carbohydrates
While leaves are the main site, photosynthesis can also occur to a lesser extent in other green parts of the plant, such as stems
. In summary, photosynthesis occurs in the chloroplasts of mesophyll cells in leaves, utilizing the thylakoid membranes for light reactions and the stroma for carbon fixation
