Photosystems in Plant Cells: Transferring Excited Electron Energy

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Discussion Overview

The discussion revolves around the mechanism of energy transfer in the photosystems of chloroplasts, specifically focusing on how the energy of an excited electron is conveyed from one chlorophyll molecule to another within the antenna complex. The scope includes theoretical and conceptual aspects of photosynthesis.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant inquires about the mechanism by which the energy of an excited electron is transferred to adjacent molecules in the antenna complex of chlorophyll.
  • Another participant explains that within PS2, energy is transferred between amino acid residues and ultimately to plastoquinone, emphasizing the role of electron-transporting molecules to direct electrons appropriately.
  • A different participant clarifies that they are specifically interested in the energy transfer process between chlorophyll molecules, noting that the electron itself is not physically transferred.
  • In response, a participant asserts that the electron is indeed physically transferred from chlorophyll P680 to pheophytin, detailing the involvement of tyrosine and manganese ions in the process.
  • Another participant expresses confusion, referencing their textbook which states that the electron is not transferred, indicating a potential discrepancy in understanding or sources.

Areas of Agreement / Disagreement

Participants express differing views on whether the electron is physically transferred or if the energy is simply handed off without physical transfer. This indicates a lack of consensus on the mechanism of energy transfer within the photosystem.

Contextual Notes

There are references to specific components and processes within the photosystem, such as P680, pheophytin, and the oxygen-evolving complex, which may require further clarification or context for complete understanding. Additionally, the discussion highlights potential discrepancies between textbook information and participant interpretations.

Who May Find This Useful

This discussion may be of interest to students and researchers in the fields of plant biology, biochemistry, and photosynthesis, particularly those exploring the mechanisms of energy transfer in photosystems.

mahela007
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How is the energy of an excited electron sent to another adjacent molecule as in the photosystem of chloroplasts in plant cells?
 
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Depends on which exact part you mean. Within PS2 it gets transferred between amino acid resides (e.g. Tyrosine) and on to reduce plastoquinone, which is what serves as the 'electron transport' to the next enzyme in the chain.

Electrons can't be allowed to move freely in the solution/cytoplasm, or they'd zoom off and reduce whatever was most reducible. So you have all these electron-transporting molecules and enzymes, to make sure the right electron goes to the right place.
 


Thanks for your reply... I'm talking about the antenna complex which "funnels" light energy to the reaction center chlorophyll.. how is energy transferred from one chlorophyll to another adjacent chlorophyll? The electron isn't physically transferred.. I'm interested in knowing how the energy of an excited electron is handed over to a separate molecule..
 


The electron is physically transferred. The excitation from light kicks out an electron from the chlorophyll P680, which goes off to pheophytin.

P680+ then gets an electron from a tyrosine, which in turn gets it from a cluster of manganese ions in the oxygen-evolving complex. Four photons makes for four electrons which results in two water molecules being reduced to an oxygen molecule.
 


my textbook says the electron is not transferred... :-|
 

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