Prokaryotes Question

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caliali612
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Prokaryotes Question

Post by caliali612 » Mon Feb 16, 2009 6:17 pm

Why do prokaryotes not have any organelles?

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MrMistery
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Post by MrMistery » Mon Feb 16, 2009 10:00 pm

cause they don't need them
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter

Stefan
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Post by Stefan » Tue Feb 17, 2009 2:26 pm

Well If u look at how the organisms evolved - u see that a first 'cell'(wasn't really a cell - couldn't divide) was called liposome - this liposom had a bilayer membrane and was filled with water full of proteins - later came DNA or RNK molecules(which was first to appear isn't really of my concern, I'm just a cytologist). So lyposomes started fusing - and had their genetic materials combined - etc etc. - And we got a first cell - prokyariotic cell - all the basic functions - and not a large energy consummation needed - usually a small cell - and when in evolution the cell of prokaryots got bigger - tahat was a problem - evolution is going in the way of surface area>>Volume - so to get their P up cell walls started to fold - creating endomembranes and thus the organells( endoplasmatic reticulum being the first) - somewhere along the way mitochondrias appeared(through endosimbiosis)! :D
Well this isn't a direct answer to your question - but I told it in there:
- Energy consumption
- Cell size - proportions - surface area>>Volume
Well u just have to look at prokaryots as a more simply organized cell...

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GaryGaulin
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Re: Prokaryotes Question

Post by GaryGaulin » Fri Feb 27, 2009 2:06 am

Wikipedia has a list of prokaryote organelles:

carboxysome - carbon fixation
chlorosome - photosynthesis
flagellum - movement in external medium
magnetosome - magnetic orientation
nucleoid - DNA maintenance
plasmid - DNA exchange
ribosome - translation of RNA into proteins
thylakoid - photosynthesis

http://en.wikipedia.org/wiki/Organelle

Contrary to common belief some prokaryotes are also reported to have membrane-bound organelles.

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Post by JorgeLobo » Fri Feb 27, 2009 12:47 pm

I'd not look to wikipedia for scientific reference. They've no organelles because that is the definition. One can always find (or imagine) divergence from almost any such definition.

There is no "why" as that presumes there's a rationale. They just don't.

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GaryGaulin
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Re: Prokaryotes Question

Post by GaryGaulin » Fri Feb 27, 2009 10:30 pm

Hi Jorge,

Sometimes Wikipedia is the best resource available. The exact same list and description is found at other sources but it's hard to say whether they are quoting Wiki or Wiki is quoting them. There are other sources of information like this:

http://library.thinkquest.org/C004535/p ... cells.html

What is now taught in (at least) US schools and even in teaching college is now obsolete. All textbooks I have seen or were described to me are wrong about this and the modern origin of life theories. I estimate they are on average 10 years behind reality.

Here is my origins presentation:

http://originofintelligentlife.blogspot.com/

That is the direction science is now going. And it was the result of over 20 years of following trends and studying things educators are not taught. So I do not pick a resource like Wikipedia and blindly believe it, I used it because it is in fact the most modern information available.

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Re: Prokaryotes Question

Post by JorgeLobo » Sat Feb 28, 2009 1:21 am

wikipedia may be an excellent source for nonscientists. To biologists, it's as trivial as the other internet sites you offer.

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GaryGaulin
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Post by GaryGaulin » Sat Feb 28, 2009 2:24 am

I understand that Wikipedia is written for the general public but that does not change the fact that at least on the internet a new scientific view is now replacing the old.

If you want to see scientists discussing the problem then here is one I found interesting:
http://scienceblogs.com/transcript/2007 ... nelles.php

Do you have a recent reliable source of information to the contrary? Without that, there is nothing I can do but assume that you were not aware of this having happened and are another attacking the messenger.

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Re: Prokaryotes Question

Post by JorgeLobo » Sat Feb 28, 2009 5:40 am

Science isn't done on the internet.

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