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The endosymbiont theory

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Stinkhorn
129943.  Fri Dec 29, 2006 11:58 pm Reply with quote

A eukaryotic cell is the basic building block of all plants, animals and fungi. It consists of a fluid known as cytoplasm that supports structures called organelles. (A diagram would have been useful here wouldn’t it…) The cell contains a nucleus, mitochondria which produce energy by aerobic resperation and, in plants, chloroplasts which produce energy by photosynthesis as well as some other structures.

A prokaryotic or bacterial cell is a much simpler kind of cell. It doesn’t contain any membrane bound organelles and has a ring of DNA instead of a nucleus.

Now for the interesting bit! Chloroplasts and mitochondria are capable of living outside of the eukaryotic cell, they can manufacture their own proteins and produce their own energy. The endosymbiont theory says that these organelles where once freeliving bacterial organisms which where engulfed by a nucleus containing eukaryotic organism but remained intact and became encorperated into the eukaryotic cell. This incorporation was mutually beneficial for both organisms and eventually they reproduced and evolved together into the eukaryotic cell we know today. Fascinating huh? Well I think so…

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smiley_face
129968.  Sat Dec 30, 2006 4:31 am Reply with quote

This is a very interesting theory indeed. Thanks for bringing that up. I'm currently reading more about it. The wikipedia article on the subject seems quite good.

However...

Stinkhorn wrote:
The cell contains a nucleus, mitochondria which produce energy by aerobic resperation and, in plants, chloroplasts which produce energy by photosynthesis as well as some other structures.

I'm going to have to disagree with you there I'm afraid. Mitochondria produce ATP in the process of respiration, and this can rightly be described as producing energy, since ATP is the energy currency of all living organisms.

However, the product of photosynthesis is glucose, a sugar which, while providing a source of energy, is not energy itself.

In order to get energy from the glucose, plants, like all eukaryotic cells, also have mitochondria to convert this glucose to ATP.

http://en.wikipedia.org/wiki/Adenosine_triphosphate
http://en.wikipedia.org/wiki/Photosynthesis

 
96aelw
129992.  Sat Dec 30, 2006 7:15 am Reply with quote

A chap walks into a shop and says "I'd like some adenosine triphosphate, please". The shopkeeper replies "Certainly. That'll be 80p".

80p sounds like ATP, you see. Thus, while the shopkeeper's reply superficially refers to the price of the requested item, it also appears, aurally, to be a definition of that item as well. On mature reflection, that one's probably funnier spoken than written down. Or perhaps merely less dreadfully unfunny. Ho hum. We live and learn.

 
gerontius grumpus
130834.  Tue Jan 02, 2007 6:37 pm Reply with quote

96aelw wrote:
A chap walks into a shop and says "I'd like some adenosine triphosphate, please". The shopkeeper replies "Certainly. That'll be 80p".

80p sounds like ATP, you see. Thus, while the shopkeeper's reply superficially refers to the price of the requested item, it also appears, aurally, to be a definition of that item as well. On mature reflection, that one's probably funnier spoken than written down. Or perhaps merely less dreadfully unfunny. Ho hum. We live and learn.


96aelw, you wouldn't happen to be Rev. Geraldine Grainger would you?

 
grizzly
130965.  Wed Jan 03, 2007 5:24 am Reply with quote

Having met 96aelw, I can confirm that he is not Rev. Geraldine Granger. However, with that much facial hair, one could only be sure by examining his figure...

 

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