Why is Chlorophyll Essential for Photosynthesis?
Chlorophyll is Essential for Photosynthesis because the Chlorophyll absorbs the electromagnetic light energy from the Sun and produces glucose through a chemical reaction or Photosynthesis. Photosynthesis is the process of nutrition that converts solar energy into chemical energy in the form of Glyceraldehyde 3-phosphate (G3P) in phototrophs with chlorophyll. Chlorophyll pigments, water, sunlight and carbon dioxide are the main four substances that are necessary for photosynthesis. Chlorophyll, the green pigments found in chloroplasts of plants and algae and in mesosomes of cyanobacteria, can absorb solar energy from sunlight and the most vital organic chemical for phototropic nutrition.
What is Chlorophyll?
Chlorophyll is the green-coloured pigment found in Chloroplast. Chloroplasts are a type of Plastid, a type of cell organelles. Plastids are mainly three types.
- Chloroplast: Chloroplast Contains chlorophyll pigment and carotenoids and it is the type of plastid that takes part in photosynthesis.
- Chromoplast: Chromoplast Contains pigments like carotene and xanthophylls. Chromoplasts are responsible for the colour variations of flowers and fruits and also help in the pollination and dispersal of seeds.
- Leucoplast: Leucoplasts are the type of plastids that are colourless and mainly functions as storage plastids. Leucoplasts are mainly three types. Amyloplasts stores starch, Proteinoplasts or aleuroplasts store proteins and Elaioplasts store fat or lipid.
The function of Chlorophyll in Photosynthesis
Photosynthesis takes place in grana located in stroma within the thylakoid. Chlorophyll molecules are rooted in the thylakoid membranes of chloroplasts.
Structure of Chlorophyll
Chlorophyll contains magnesium (Mg++), as a central metal atom. The magnesium atom is surrounded by a nitrogen based structure which is known as porphyrin ring. Chlorophyll contains a fifth pyrrole that forms the ring. This pyrrole absorbs solar energy. The chlorophyll function like photosynthetic pigments, embedded in chloroplasts. These Chlorophyll are outstanding photosensitizer.
Types of Chlorophyll
- Chlorophyll a is found in all beings that perform oxygenic photosynthesis like plants, algae, cyanobacteria.
- Chlorophyll b is found in green algae.
- Chlorophyll c is found in diatoms.
- Chlorophyll d is only found in red algae.
Out of these types, Chlorophyll a and Chlorophyll b are the most common type of Chlorophyll.
Chlorophyll a and Chlorophyll b
The photosynthetic reaction centers are found in two photosystem units – Photosystem I and Photosystem II. These are P700 and P680. Chlorophyll b and chlorophyll a are found here, respectively.
Similarities of Chlorophyll a and Chlorophyll b: They don’t emit the absorbed light energies.
Chlorophyll a and b are almost similar in features with small differences:
|Chlorophyll a||Chlorophyll b|
|There is a methyl (-CH3) group attached with third carbon in a side chain as the methanol surrounds it||There is an aldehyde (-CHO) group attached with third carbon in a side chain as acetone surrounds it.|
|It is the primary photosynthetic pigment.||It is an accessory photosynthetic pigment.|
|It absorbs orange-red and violet-blue rays from sunlight.||It absorbs blue and red rays.|
|Colour: Bluish-green||Colour: Olive green|
Chlorophyll serves three main functions at the primary level of Photosynthesis:
- Chlorophyll Essential for Photosynthesis as Chlorophyll molecules gets excited after absorbing sunlight or solar energy.
- It transfers the absorbed light energy to the photosynthetic reaction centre through the resonance energy transfer process.
- In the photosynthetic reaction centre, a specific pair of chlorophyll (Chlorophyll a and Chlorophyll b) receives those charged protons and extracts the charge from them via biosynthesis.
It is a very complex reaction that occurs under the thylakoid membrane. The charge of the chlorophyll is being extracted in the photosynthetic reaction centres. This process is called charge separation. P680 and P700 then transfer the charge to a series of electrons extracted from water molecules. This process continues to create an electron transport chain. These electrons help to produce oxygen (O2) and a charged hydrogen atom (H+). Therefore the splitting of water occurs through the absorbed solar energy and the water molecule splits into hydrogen and oxygen through the release of energy. This process is known as Photolysis of Water.
The chlorophyll pigments of P680 and P700 pumps the H+ ions all over the thylakoid membrane to produce ATP and NADPH.
ATP or Adenosine triphosphate and NADPH (Nicotinamide Adenine Dinucleotide Phosphate Hydrogen) are chemical compounds to store the energy collected from the sunlight and processed through photosynthesis. This energy is supplied to chloroplasts to make starch from carbon dioxide (CO2). This starch stores the energy collected by ATP and NADPH in fruits, roots and stem.
Why is chlorophyll needed for photosynthesis?
- It absorbs solar energy from sunlight.
- The charge is transferred through chlorophyll from the outer surface of leaves and green parts of a plant.
- The absorption of orange-red and violet-blue rays by chlorophyll is one of the optimal functions of photosynthesis. Chlorophyll does not emit these rays.
- Chlorophyll a transfers the energy with help of chlorophyll b.
- Chlorophyll b absorbs blue and red light and emits green in colour.
- The process of starch creation takes place in chloroplasts.
The article ‘Why is Chlorophyll Essential for Photosynthesis?’ will help you to understand the essential role of Chrlolophyll in Photosynthesis and give you a comprehensive idea on ‘Why is Chrlolophyll important in Photosynthesis?’.