Quantasome Diagram, Structure and Function

In this article we will discuss about quantasome diagram, discovery, structure and function

What is Quantasome?

• Inner surface of thylakoid membrane consists of small spherical structure is known as Quantasomes.
• Quantasomes are also known as photosynthetic units.
• Each quantasomes approximately contain 200 to 300 chlorophyll molecules.

Quantasome Diagram

Discovery of Quantasomes

• In 1952, Steinman observed granular structures in chloroplast lamellae using an electron microscope.
• These structures were later confirmed by Park and Biggins (1964) as the physiological units of photosynthesis. They named these units quantasomes.
• According to them one quantasome contains about 230 chlorophyll molecules.
• Emerson & Arnold discovered fixing one molecule of CO2 required 2500 chlorophyll molecules.
• Therefore, approximately 10 quantasomes are required to fix one CO2 molecule.
• However, the reduction or fixation of one CO2 requires 10 quanta of light and so each unit would contain 1/10 of 2500 i.e. 250 molecules.
• According to Emerson 8 quanta of light are required for the release of one oxygen molecule or reduction of one Carbon dioxide molecule.
• The quantum yield is 1/8 or 12 %.
• No of quantum energy are utilizing to produce one molecule of oxygen is called quantum yield.

Quantasome Structure

The structure of a quantasome within thylakoid membrane consists of following parts:

• Photosynthetic Pigments : Photosynthetic pigment such as chlorophyll and carotenoids are embedded in quantasome.
• Light Harvesting Complex (LHC): They are made up of accessory pigments and some protein molecules.
• Reaction Centers: Reaction centers are made up of chlorophyll a molecules.
• Electron Transport Chain: Within the quantasome, occur the light reactions of photosynthesis.
• Protein Matrix: Protein matrix that provides structural support and stability to the photosynthetic molecules.

Quantasome Function

• The photosynthetic pigments are present in quantasomes are responsible for absorbing light energy from the sun light.
• LHC in quantasome capture sun light and transfer it to the reaction centers.
• They help in converting light energy into chemical energy.

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