Internal Structure of Chloroplast


 
 
Concept Explanation
 

Internal Structure of Chloroplast

Chloroplasts are plant cell organelles that covert light energy into relatively stable chemical energy via the photosynthetic process. 

Chloroplasts 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.

Structure of chloroplast 

  • Chloroplast are minute oval bodies bounded by a double membrane, and their interior contains closely packed flattened sacs(thylakoids) arranged in piles(grana) lying in a colourless ground substance called stroma. Ordinarily, there may be 40- 50 chloroplasts in a cell.
  • The pigment chlorophyll is contained in the walls of thylakoids. It is highly complex substance, composed of carbon, hydrogen, oxygen, nitrogen and magnesium.
  • Chloroplasts are mainly contained in the mesophyll cells located between the upper epidermis and the lower epidermis of leaves. These are also found in the guard cells of stomata and in the outer layers of young green stems.
  • There may be more than 500,000 chloroplasts per sq.mm. of leaf surface.
  • You will be surprised to know that there are nine types of chlorophyll. Two out of these, chlorophyll a and chlorophyll b are best known and most abundant.
  • Chlorophyll is highly sensitive to light, so too much light may destroy it. However, the formation of chlorophyll itself depends on the exposure of the plant of light. The grass growing in the shade under a stone turns yellowish due to the non formation of new chlorophyll and due to the disintergration  of the older one in the absence of light.

                                            

     
     
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