explain photosystem. please explain using these terms a-emerson effect b-PSU c-quantosomes

explain photosystem.
please explain using these terms
a-emerson effect


1 Answers

Aabid Hussain
askIITians Faculty 576 Points
6 years ago
Hi Soumya,

Thank you for asking!

First of all let me make you clear about what are Photosystems, then i will focus over Photosynthetic unit (PSU) and quantasomes.

Photosystem (Defination):It is the structural and functional unit of photosysnthesis where the event of light absorption and transfer of electrons takes place.

Photosystem(s) is/are composed of discrete protein complexes embeded within the thylkoid membrane.

Photosynthetic unit (PSU): A hypothetical light-harvesting unit of photosynthesis that, in green plants, comprises about 300 light-absorbing molecules with a molecule of chlorophyll acting as the reaction Centre.
There are thought to be two different phosynthetic units, one for each of the photosystems (PS I & PS II).

Before coming to the next point about quantasome, let me first make it clear that lights emits energy in the form of tiny hypothetical packets which is also called as Quanta (singular= quantum). Proposed by Max Plank.

Quantasome:Quantasome: A particle that is embedded in a paracrystalline array on the surface of thylakoid discs in chloroplasts. Quantasomes are composed equally of lipids and proteins, which include various photosynthetic pigments and redox carriers. For this reason, they are considered to be photosynthetic units. They occur in 2 sizes: the smaller quantasome is thought to represent the site of photosystem I, the larger to represent the site of photosystem II.

Robert Emerson while his research over the yield of photosythesis observed that the total yield (CO2 fixation) of the photosynthesis showed a great increase when the chlorella is exposed to alternate wavelength (far red and short). This effect is named as Emerson effect.

Hope the answer of the question.

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