Jumat, 11 Oktober 2013

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Photosynthesis Pigment, Structure Of Chloroplast


Photosynthesis Mechanism In green Plant
Photosynthesis Mechanism In green Plant. Through the Help of sunlight, carbon dioxide and water can be converted into glucose

Photosynthesis only occurs in the cells that have photosynthesis pigment, particularly chlorophyll.

The chlorophyll (green pigment of leaf) can be found mostly in leaves. The leaves are composed of palisade tissue and spongy tissue containing chloroplast (plastid). How is the structure of chloroplast?

The structure of chloroplast

From the structure, chloroplast consists of double membrane covering a chamber filled with liquid called stroma. The stroma is the enzyme-rich liquid where glucose formation takes place in photosynthesis. Besides stroma, in the chloroplast there is also found thylakoid and grana. Thylakoid, membrane is the part of chloroplast with disc-shaped structure. Chlorophyll and other pigments, such as carotene and xanthophylls, usually attach to the thylakoid membrane. Some thylakoid membranes axe often arranged in stack called grana (plural granum). 

AII pigments attaching to thylakoid membrane are able to absorb light energy of the sun and use it in photosynthesis. Chlorophyll a absorbs blue-purple and red lights. Chlorophyll a has green color because it reflects green light. Chlorophyll b absorbs blue and orange light and reflects green-yellow light. White carotene that has red-yellow color absorbs green-blue light.

The Chlorophyll reflects green light

when a pigment absorbs light, one out of the three things will occur.

  • First, the absorbed energy is released as heat. 
  • Second, the absorbed energy is directly passed through with longer wave, which is called fluorescence. 
  • Third, the absorbed energy triggers a chemical reaction such as photosynthesis.

Source: Biology, Concepts & Connection, 2006. 

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