CHLOROPLASTS Chloroplast
• Chloroplast is a structure within the cells of plants and green algae that is the site
of photosynthesis
• They are organelles that conduct photosynthesis, where the photosynthetic
pigment chlorophyll captures the energy from sunlight, converts it, and stores it in
the energy-storage molecules ATP and NADPH while freeing oxygen from water
in plant and algal cells.
• They then use the ATP and NADPH to make organic molecules from carbon
dioxide in a process known as the Calvin cycle. Chloroplast - Distribution
In plant cells, chloroplasts are homogeneously distributed in the cytoplasm though
in certain plant cells they may remain concentrated around the nucleus. in the cell
cytoplasm, they have definite orientation.
Chloroplasts are motile organelles consequently, they show both passive and
active movements. The chloroplasts are located in the mesophyll region, between the upper and the
lower epidermis.
It is made up of of several layers of loosely arranged spongy parenchyma cells with
intercellular spaces.
The mesophyll region is the chief photosynthetic tissue of the leaf because of the
presence of chloroplasts.
In a single mesophyll cell, the number of chloroplast ranges from 1 to 50. This
number may vary from cell to cell depending on plant species, age, and health of
the cell.