Mesosome in prokaroytes Watch

Kinyonga
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In my biology book and on a couple of websites I find a description of mesosomes to be "areas in the cell membrane of prokaroytic bacterial cells that fold inward. They play a role in cellular respiration."
However, Wikipedia says: "Mesosomes are folded invaginations in the plasma membrane of bacteria that are produced by the chemical fixation techniques used to prepare samples for electron microscopy. Although several functions were proposed for these structures in the 1960s, they were recognized as artifacts by the late 1970s and are no longer considered to be part of the normal structure of bacterial cells."
I'm guessing Wikipedia's right, but I'd like a second opinion on this!
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OxFossil
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(Original post by Kinyonga)
In my biology book and on a couple of websites I find a description of mesosomes to be "areas in the cell membrane of prokaroytic bacterial cells that fold inward. They play a role in cellular respiration."
However, Wikipedia says: "Mesosomes are folded invaginations in the plasma membrane of bacteria that are produced by the chemical fixation techniques used to prepare samples for electron microscopy. Although several functions were proposed for these structures in the 1960s, they were recognized as artifacts by the late 1970s and are no longer considered to be part of the normal structure of bacterial cells."
I'm guessing Wikipedia's right, but I'd like a second opinion on this!
From a google scholar search, it appears that most references to the mesosome as a definite, recognised structure in prokaryotes appear in non-specialist texts, like your AS textbook. But as Wiki says, the consensus amongst microbiologists seems to be that that they have only dubious status. Here's some notes from a 2018 university lecture;

"Mesosomes are membranous folds extending into the cytoplasm of some prokaryotic cells (Gram-positive cells) following chemical
fixation. Since prokaryotic cell membranes contain enzymes involved in ATP synthesis via oxidative phosphorylation, these were thought to be analogous to the cristae of mitochondria...Some mesosomes appear to contact the covalently closed, circular DNA molecules of prokaryotic cells so were thought to aid in chromosome separation during cell division. Following advances in cell preparation for electron microscopy during the1980s, it was concluded that mesosomes are most likely artifacts formed due to damage to the cell membrane following chemical fixation. Most researchers currently agree that mesosomes do not exist within living
cells"
However, I also found at least one recent (2014) research paper that discussed mesosomes as functional structures involved in hydrogen peroxide production. So their status doesn't seem entirely settled.
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Kinyonga
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(Original post by OxFossil)
From a google scholar search, it appears that most references to the mesosome as a definite, recognised structure in prokaryotes appear in non-specialist texts, like your AS textbook. But as Wiki says, the consensus amongst microbiologists seems to be that that they have only dubious status. Here's some notes from a 2018 university lecture;

"Mesosomes are membranous folds extending into the cytoplasm of some prokaryotic cells (Gram-positive cells) following chemical
fixation. Since prokaryotic cell membranes contain enzymes involved in ATP synthesis via oxidative phosphorylation, these were thought to be analogous to the cristae of mitochondria...Some mesosomes appear to contact the covalently closed, circular DNA molecules of prokaryotic cells so were thought to aid in chromosome separation during cell division. Following advances in cell preparation for electron microscopy during the1980s, it was concluded that mesosomes are most likely artifacts formed due to damage to the cell membrane following chemical fixation. Most researchers currently agree that mesosomes do not exist within living
cells"
However, I also found at least one recent (2014) research paper that discussed mesosomes as functional structures involved in hydrogen peroxide production. So their status doesn't seem entirely settled.
Thanks for your help! I suppose if the question ever comes up I'll just make sure I stress their ambiguity of their function.
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OxFossil
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(Original post by Kinyonga)
Thanks for your help! I suppose if the question ever comes up I'll just make sure I stress their ambiguity of their function.
It's a long time since I had anything to do with school exams, so have no useful words of advice on how far to go. I imagine your textbook will reflect the "main line" of the answer required. Interesting question though; it's good that you've been interested enough to do a bit of background reading.
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