Explain how the CHLOROPLAST adapted to its functions?
Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide to produce sugars. Chloroplasts capture light energy from the sun to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis. Chloroplast has the following features to fulfill its function of photosynthesis process:-
1.Presence of membrane: The membrane of the chloroplasts is semi-permeable, and it regulates the entry and exit of molecules from the chloroplast. In addition, they are the site for synthesis of certain lipid molecules as well pigments like carotenoids that are required for light harvesting.
2.Presence of grana: Grana is the site of light-dependent reactions of photosynthesis and the associated photosystems. This is where photosynthetic pigments like chlorophyll and carotenoids, absorb light energy, which is then used to break down water molecules, and ultimately give rise to ATP, NADPH2 and oxygen.
3.Presence of stroma: it is the site for the dark or light-independent reactions of photosynthesis. The enzymes in the stroma utilize carbon dioxide from the atmosphere, as well as the ATP and NADPH2 molecules released from grana, to synthesize sugar molecules and starch. This process is also known as carbon dioxide fixation, and occurs through a series of reactions collectively called Calvin cycle.
4.Presence of photosynthetic pigments: Chlorophyll and carotenoids are both photosynthetic pigment found in chloroplast, that are involved in photosynthesis. Both chlorophyll and carotenoids are responsible for harvesting light, absorbing photons and transferring the excitation energy to the photosynthetic reaction center