What came first? The chloroplast or the mitrochondria?

[Bluenoise]

It hasn't been proven either way. I have my opionion but what's your'se?

 

p.s. (I would have posted this in the poll forum but there's so rediculousness about have to do it by correspondance to an admin, Hmmmm I wonder why there's only been 1 new poll posted in the last 3 months.) But anyways this forum is appropriate enough.

[ecoli]

heterotroph hypothesis, man!

[Bluenoise]

"heterotroph hypothesis"

 

That gives the order of emergence of heterotrophs and photosyntetic bacterium. Neither of which contain mitochondria or chloroplasts...

[rakuenso]

if you can find an eukaryotic cell with a choloroplast but no mitonchondria, then i'll think otherwise

[ecoli]

early heterotrophs are though to actually be the predecesors of mitochondria. Similarly, photosynthetic bacteria probably evolved into chloroplasts.

[Bluenoise]

Right but since they both existed before either mitochondria or chloroplast the heterotrop hypothesis does nothing to answer the question. Anyways I voted same as you guys, since it's more likely. I'm trying to get some alternative opinions.

[RyanJ]

It was the chloroplast ad plants were actually the first things to form, thus the reason we are here. there were these little tiny plants called algea that took Carbon Dioxide form the air, produced Oxygen as a result although the Oxygen was toxic to these and the buildup eventually caused them to be wiped out but there we go Oh and this was actually the start when those heavy Iron(III) Oxide deposits were formed. All that Iron in the ocean was oxiudused by the now dissolved oxygen forming rust, Iron(III) Oxide and thus accounting for theose lovley red rocks we find! This is the first case of anyhting affecting the climate on a global scane and it allowed us to evolve!

 

Well... they were not plants as such but were photosynthesising algea

 

Also, if you look at bacteria you'll find they are prokaryotes - they do not have organells but algea do. If you olook at bacteria you'll find they still don't have mitocondria... (Reference here )

 

Cheers,

 

Ryan Jones

[Conceptual]

I agree with RyanJ in that the chloroplast probably came first. The reason being the solar potential. This was probably the major energy source that was acting on the evolving pre-cells. The mitochondria would have evolved due to the chloroplast food output within the water. This would create a new chemical potential within the water from which the mitochondria could evolve.

[Mokele]

Except that the ancestor of the chloroplast would not have leaked food into the water, but kept it for itself. Otherwise, how would it survive? Organisms do no exist solely for the benefit of others. Even in symbiotic relationships, the goal is, at the end, evolutionarily selfish.

 

Mokele

[RyanJ]

Except that the ancestor of the chloroplast would not have leaked food into the water' date=' but kept it for itself. Otherwise, how would it survive? Organisms do no exist solely for the benefit of others. Even in symbiotic relationships, the goal is, at the end, evolutionarily selfish.

 

Mokele[/quote']

 

Yea true but some of this would have leaked into the water and also the oxygen released by it would have caused the oxygen levels in the atmosphere to rist.

 

How could the mitocondria work with out the oxygen to work the aerobic respiration?

 

Cheers,

 

Ryan Jones

[Skye]

It was the chloroplast ad plants were actually the first things to form' date=' thus the reason we are here. there were these little tiny plants called algea that took Carbon Dioxide form the air, produced Oxygen as a result although the Oxygen was toxic to these and the buildup eventually caused them to be wiped out but there we go Oh and this was actually the start when those heavy Iron(III) Oxide deposits were formed. All that Iron in the ocean was oxiudused by the now dissolved oxygen forming rust, Iron(III) Oxide and thus accounting for theose lovley red rocks we find! This is the first case of anyhting affecting the climate on a global scane and it allowed us to evolve!

 

Well... they were not plants as such but were photosynthesising algea

 

Also, if you look at bacteria you'll find they are prokaryotes - they do not have organells but algea do. If you olook at bacteria you'll find they still don't have mitocondria... (Reference here )

 

Cheers,

 

Ryan Jones

Hey Ryan, while they are often called "blue-green algae", I believe what you are talking about are cyanobacteria. They aren't actually algae, and don't contain organelles, they are bacteria. They just look like algae when they are in the water, so people call them that.

[RyanJ]

Hey Ryan, while they are often called "blue-green algae", I believe what you are talking about are cyanobacteria. They aren't actually algae, and don't contain organelles, they are bacteria. They just look like algae when they are in the water, so people call them that.

 

So thats their name? OK, thanks

 

Cheers,

 

Ryan Jones

[shenzhou]

I think the best answer is that mitochondria came first and by quite a long time.

 

Mitochondria are found in every eukaryote (they have been lost in a few but there are still vestiges) but chloroplasts are found only in a few which suggests that chloroplasts evolved after many groups of eukaryotes had diverged. I suppose chloroplasts could have been lost indipendantly in many groups of eukaryotes but this hypothesis is extremely unlikely.

 

Extant eukaryotes without chloroplasts have no trace of chloroplast genes in their genome which is what you would expect to find if they ever had them. There are a small number organisms like the malaria parasite that have the vestiges of a functional chloroplast (apicoplast) and chloroplast genes in their genome.

 

Chloroplasts have a much larger genome and more bacterial features than mitochondria indicating these have had less time to decay and for the transfer of genes to the nucleus. This indicates chloroplasts are younger than mitochondria.

[RyanJ]

I'm shure that mitocondria were formed first (And my biol teacher agress with me on this one) because they released the oxygen that allows aerobic respiration to take place, without which the miocondria would not function.

 

Correct me if I'm wrong but doesn't aerobic respiration require oxygen? If so then the answer must be that somethign like a chloroplast formed first.

 

Cheers,

 

Ryan Jones

[Labrador]

As far as I know green algae and thus plant chloroplasts evolved from a group of photosynthetic bacteria called prochlorophytes (are they cyanobacteria? The literature I'm reading isn't very clear on this, but I guess they are...) which have as photosynthetic pigments chlorophylls a and b and carotenoids (no phycobilins!), such as green algae and plants do. However, I am not 100% sure if the reading I made from the literature is correct, especially in whether prochlorophytes are cyanobacteria or not. So, am I right? I'd like to hear your opinion. Thanks.

 

PS - I'm an undergraduated student taking college's 1st year on Microbiology at Lisbon's University Faculty of Medicine (Medical School).

[BioNerd]

What is the point of forming glucose via photosynthesis if a cell cannot use it via glycolysis?

Yes, glycolysis happens in the cytosol, as does anaerobic respiration. However, aerobic respiration occurrs in the mitochondrion. Let's think about this for a minute - aerobic respiration = oxygen needs to be present. Glycolysis from photosynthesis-formed glucose = no need for oxygen. I have changed my opinion from mitochondria evolving before chloroplasts due to this evidence to the chloroplasts forming first.

 

Another thing to ponder - mitochondria have two lipid membranes while chloroplasts have three.

And hasn't anyone heard of the endosymbiont theory?

[RyanJ]

@BioNerd: Exactly what I said

 

Makes perfect sence when you say it

 

Cheers,

 

Ryan Jones

[shenzhou]

I have changed my opinion from mitochondria evolving before chloroplasts due to this evidence to the chloroplasts forming first.

 

But there was oxygen before mitochondria evolved - it was produced by bacteria that included the ancestors of chloroplasts - but these bacteria were independant of eukayotic cells and so were not chloroplasts yet.

 

And hasn't anyone heard of the endosymbiont theory?

 

Yes that is almost certainly how mitochondria and chloroplasts evolved.

[RyanJ]

But there was oxygen before mitochondria evolved - it was produced by bacteria that included the ancestors of chloroplasts - but these bacteria were independant of eukayotic cells and so were not chloroplasts yet.

 

Actually the basic oxygen in out atmosphere (Or most of it wanyway) was formed from chloroplasts and not through cells themselves. The record shows that there were baceria arround for a while before they evolved and in this time the oxygen level did not rise then when the invention of the chloroplast came along the Oxygen levels shot up killing 98% of the species on the planet at that time but alowing people to form!

 

Cheers,

 

Ryan Jones

[shenzhou]

Actually the basic oxygen in out atmosphere (Or most of it wanyway) was formed from chloroplasts and not through cells themselves.

 

This may be true (although how could you tell) but there is evidence of local oxic conditions - probably a thin layer of oxygenated water at of near the surface of the sea before atmospheric oxygen began to rise, and before the fisr chloroplasts. It is in such places where early eukaryotes with mitochondria could have evolved. Interestingly several modern organsism have evolved endosymbioses with bacteria and these organisms almost always live near an oxic/anoxic border - it is these conditions rather than just plentiful oxygen that encourage endosymbiosis.

 

The record shows that there were baceria arround for a while before they evolved and in this time the oxygen level did not rise

 

There is evidence of local oxic conditions and there were also massive chemical sinks that reacted with oxygen preventing it becoming common in the atmosphere for a long time.

 

then when the invention of the chloroplast came along the Oxygen levels shot up killing 98% of the species on the planet at that time but alowing people to form!

 

I don't think any extinction has been linked just to oxygen - the extinction at the beginning of the cambrian occured at the same time as a rise in oxygen but there was also a massive increase in predators and competitors and i don't think the two can be separated as a cause of that extinction.

 

see: The geological consequences of evolution (free pdf) : http://www.blackwell-synergy.com/links/doi/10.1046%2Fj.1472-4669.2003.00002.x

[RyanJ]

This may be true (although how could you tell) but there is evidence of local oxic conditions - probably a thin layer of oxygenated water at of near the surface of the sea before atmospheric oxygen began to rise' date=' and before the fisr chloroplasts. It is in such places where early eukaryotes with mitochondria could have evolved. Interestingly several modern organsism have evolved endosymbioses with bacteria and these organisms almost always live near an oxic/anoxic border - it is these conditions rather than just plentiful oxygen that encourage endosymbiosis.

[/quote']

 

There are currently onely one way: volcanic rock. When it is thrown to the surface it cools rapidly and seals in small ammounds of the air from the time thus alloing us to tell what the air was like back then - not somehting you;d like to try and live in

 

I don't think any extinction has been linked just to oxygen - the extinction at the beginning of the cambrian occured at the same time as a rise in oxygen but there was also a massive increase in predators and competitors and i don't think the two can be separated as a cause of that extinction.

 

see: The geological consequences of evolution (free pdf) : http://www.blackwell-synergy.com/links/doi/10.1046%2Fj.1472-4669.2003.00002.x

 

I'll read the PDF!

 

Again - this is what was said on a show about the evolution of life. I'll see if I can find the show from my collection tonight and get an exact quote (Incase I can't find it it was a BBC documentart about 4 years ago).

 

I actually remember the presenter saying that it was because the Ocygen biproduct was toxic to the bacteri (Or whatever it was that made it) and when the levels got to a certain level it killed most of them. The only ones that survived were the new oxygen users.

 

The BBC are reliable with their information so I don't know...

 

Cheers,

 

Ryan Jones

[Nashyboyo]

The mitochondrion is thought to have arrisen by endosymbiosis. This hypothesis , by definition states that a prokaryote entered a eukaryote by endocytosis and developed together as one body via mutual gain from one another. As mentioned earlier in this thread, scientists noticed a double membrane one being less permeable than the other, suggesting endocytosis. Also the fact that the mitochondrion has its own source of DNA thus a possible prokaryote.

 

The chloroplast has a similar story thus why this poll exists.

 

I'm voting for chloroplasts because I believe (as mentioned earlier in this thread) the utilisation of solar light energy by evolution seems more likely to have occured first in time due to the fact that it seems a much more primative method of surrival as opposed to the symbiosis of a heterotroph and a eukaryotic cell.

 

I noticed earlier in this thread that someone was talking about oxygen not being needed for photosynthesis. Your both correct and incorrect. Ask yourself "How does a plant survive at night?".

 

Once glucose is produced it is converted to starch to oppose any osmotic potential which may form. This store of starch is then utilised by plants along with oxygen via aerobic respiration.

[shenzhou]

I'm voting for chloroplasts because I believe (as mentioned earlier in this thread) the utilisation of solar light energy by evolution seems more likely to have occured first in time due to the fact that it seems a much more primative method of surrival as opposed to the symbiosis of a heterotroph and a eukaryotic cell.

 

For the chloroplast to have evolved first it must have been lost independantly in every eukaryotic lineage that currently does not contain chloroplasts leaving no trace behind - This scenario is extremely unlikely. In the few eukayotes that have lost mitochondria there are genetic traces - there are no such vestiges of chloroplasts in the vast majority of eukaryotes lacking plastids.

 

Also the chloroplast retains more bacterial DNA and bacterial features than mitochondria again suggestive of a more recent origin.

 

Only if you ignore the features of chloroplasts and mitochondria and parsimony can you argue for chloroplasts first.

[Nashyboyo]

For the chloroplast to have evolved first it must have been lost independantly in every eukaryotic lineage that currently does not contain chloroplasts leaving no trace behind - This scenario is extremely unlikely. In the few eukayotes that have lost mitochondria there are genetic traces - there are no such vestiges of chloroplasts in the vast majority of eukaryotes lacking plastids.

 

Could you expand on this please

 

Also the chloroplast retains more bacterial DNA and bacterial features than mitochondria again suggestive of a more recent origin.

 

I don't understand how this is so ? If the organellar DNA is required for co-localisation then it will remain. How is this a measure of time?

 

http://www.journals.royalsoc.ac.uk/media/pe6ptnwrwl0f73yyrqau/contributions/9/f/l/d/9fldlqblxbxg0y5u.pdf

 

The chloroplast retains more DNA for redox controlled expression (co-locally) for the principles described in the above journal.

[drirakumas]

what would be the result when chloroplast been injected into the egg? will number of chloroplast increase or not after few days?