Our Biosphere contains all biotic and abiotic factors, and talking about abiotic. They depend entirely on biotic (or living) factors for survival.
Key Takeaways
- Photosystem I is responsible for the production of NADPH, while photosystem II produces ATP.
- Photosystem I is associated with photosystem II in the electron transport chain, while photosystem II works independently.
- Photosystem II is sensitive to herbicides, while photosystem I am not.
Photosystem I vs. Photosystem II
Photosystem I (PS I) is the second protein complex in the light-dependent reactions of photosynthesis. It is located in the thylakoid membrane. Photosystem II (PS II) is the first protein complex in the light-dependent reactions of photosynthesis. It is located in the thylakoid membrane and is responsible for the initial capture of light energy.
Photosystem I is also written as P700. Its primary function is to form a molecule of NADPH. The immediate electron acceptor of Photosystem I is Plastocyanin.
The primary function of the Photosystem is to perform hydrolysis of water along with ATP synthesis. The immediate electron acceptor of the same is Plastoquinone, and the three primary electron acceptors of Photosystem II are – Unknown Q, Plastoquinone, and Cytochrome b559.
Comparison Table
| Parameters of Comparison | Photosystem I | Photosystem II |
|---|---|---|
| Present In | Photosystem is present in the granum and stroma thylakoid. | Photosystem II is present in the granum thylakoid only. |
| Wavelength Absorb | It absorbs a wavelength of about 700nm. | It absorbs a wavelength of about 680nm. |
| Number of Electron Carriers | It has six total electron carriers. | It has three electron carriers in total. |
| Electron Acceptor | Plastocyanin | Plastoquinone |
| Formation of NADPH | The end product is NADPH. | There is no formation of NADPH. |
| Reaction Centre | P700 nm | P680 nm |
| Photolysis of Water | Photosystem I is not used in the photolysis of water. | Photosystem II is used in photolysis. |
| Content of Chlorophyll | The content of chlorophyll a is more compared to the chlorophyll b content. | The content of chlorophyll b is more than chlorophyll a. |
What is Photosystem I?
Photosystem I is present in the granum thylakoid and stroma thylakoid of green plants and algae. Photosystem I contain two components – Photosynthetic Unit and Electron Carrier.
Photosystem I comprises two protein-rich subunits, which are – psaA and psaB. It absorbs a wavelength of about 700nm.
The function played by the Photosystem is that it helps in the formation of NADPH and ATP in the light reaction.
What is Photosystem II?
Photosystem II is present in granum thylakoid only in green plants and algae. It also contains two components, Photosystem I: Photosynthetic Unit and Electron Carrier.
The reaction center consists of chlorophyll, a molecule that absorbs the wavelength of 680nm, while the light-harvesting complex has 200 molecules of chlorophyll a and b.
The core composition of the photosystem is said to be made up of two subunits named D1 and D2. It is a membrane-embedded protein complex with 20 subunits and more than 50 cofactors.
The primary role performed by Photosystem II is that it helps in the hydrolysis of water and ATP synthesis in the mitochondria.
Main Differences Between Photosystem I and Photosystem II
- The location of the presence of Photosystem I is that it is present in the stroma and granum thylakoid, while Photosystem II is present only in the granum thylakoid.
- The wavelength at which Photosystem I is 700nm, while at which Photosystem II is 680nm.
References
- https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1399-3054.1992.tb01328.x
- https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201303671
- https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1751-1097.1987.tb08413.x
- https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1399-3054.1991.tb05101.x
Last Updated : 11 June, 2023
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
I find the thorough comparisons between Photosystem I and Photosystem II extremely enriching and thoughtfully presented.
Absolutely, it’s an excellent rundown of the topic.
It definitely has that great balance between informativeness and accessibility.
It’s evident a lot of effort went into this article, but it’s not the most captivating read.
The content itself is fascinating, but the delivery could be improved for a more engaging read.
There’s always room for improvement when it comes to scientific writing, especially in terms of engagement.
The article provides a great deal of information, but it’s definitely heavy on the technicalities.
There’s definitely a niche audience for these in-depth, technical discussions.
It’s a matter of perspective, that level of detail will appeal to some readers more than others.
While I appreciate the thorough detail, it’s presented in a way that can be off-putting to many readers.
This is frustratingly complicated, it’s just not digestible for the average reader.
It’s okay to struggle with complexity, Stewart. Sometimes it just takes time and extra reading to fully grab the concepts.
I’m sorry you feel that way! I found it quite enlightening.
This is an important subject, but the article is so dry and lacking in fire, it’s hard to get motivated about it.
The usual struggles of scientific writing, isn’t it? It’s hard to liven up these types of articles.
I see where you’re coming from, but it’s the nature of the content. It’s just factual and scientific.
Super interesting content! I personally did not know much about this, so it was a good read. Thanks!
Learning so much from this. It’s quite surprising to see how complex photosynthesis is.
Totally agreed! I found this to be extremely informative and well-written.
The contrasting details between Photosystem I and Photosystem II are meticulously laid out, making the article a valuable read.
Precisely! It’s a commendable effort in breaking down complex processes.
It’s a great reference for anyone diving into the depth of photosynthesis.
I’m not sure how to feel about this article. It’s not the most engaging content.
I can see that, Thomas. Not every scientific piece can be turned into a gripping story.