The Mystery of the Mitochondrion...

*In advance, this is my first thread on ATS. While I believe I have a grasp on the guidelines, please excuse any non-working links or such that may take me a while to figure out. Also, this topic may be based in a science with big words, but if you wade through the information, it just may lead you to think about things a little differently. Everything I am presenting to you is scientific fact, it just may be me seeing it a little differently )

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The human understanding of the building-blocks of the world around us is at a higher point than any time in history.

We have mapped the genome, and can even give you a test to tell you what diseases you are likely to die from.

And yet to me, one of the largest mysteries still to be fully researched is one that we discovered back in the 1840's... Mitochondria.

Wiki - Mitochondrion

Most complex organisms on Earth that contain nucleic cells are actually made of two organisms on a cellular level. In a simpler way, there are two types of cells: Nucleic cells (Eukaryotes), and non-nucleic cells (Prokaryotes). All complex organisms are Eukaryotes, and most contain Mitochondria.

The strangeness begins when you realize that Mitochondria are actually nothing more than a Prokaryote that has, through some form of evolution or another, become bonded in a symbiotic relationship with the Eukaryotic cell that it inhabits.

Origin of the Mitochondrion

It is unclear whether the Prokaryotes directly evolved into Eukaryotes, or whether they took advantage of the relationship at a later time, but we do know that they are in essence two separate organisms... the Mitochondria being evolved from a bacteria.

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Function of Mitochondria:

The basic function of the Mitochondria is energy conversion and metabolism control. The creation of energy in Eukaryotic cells is known as the Krebs Cycle.

The creation of energy is normally accomplished through cellular respiration, which is basically the conversion of oxygen and acetate/sugars into energy. It was once believed that all mitochondria required cellular respiration, and the use of oxygen... but it is now known that mitochondria are capable of producing limited energy with no oxygen present at all, at least in certain plants (Rice and Barley).

It is even known that when oxygen is limited in other organisms, that some nucleic cells have the option of producing energy completely independent of the mitochondria (Anaerobic Cellular Respiration.

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Origin of Cells:

Now, the oldest known cellular fossils are around 3.8 billion years old! To put this in perspective, the oldest known rocks ever discovered are 3.96 billion years old. At 3.5 billion years we can even already see Cyanobacteria, that is, blue-green algae. In the grand time-scale of things, the original cooling of our planet is very close to the original existence of life itself. Earliest Life

These earliest cells were also already quite complex and are therefore believed to have already evolved from an early form. Of course, we have yet to actually discover any earlier cells, at least on Earth. We'll get back to this in a moment.

So now we have the almost synchronized timings of the original formation of the first solid rocks (and presumably the atmosphere), and also the creation of the first known life on the planet. What was the catalyst?

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Older than Earth?:

So if the oldest known cells on Earth are already quite old and complex, where have we seen evidence of earlier, smaller cells? A Martian meteorite known as ALH 84001.

*In the fairness of transparency, I will say that it can not be 100% proven that these fossils are ancient bacteria. But what can be 100% proven is that they look like other known bacteria, that they have the same size proportions to other known bacteria, that they show signs of colonizing like known bacteria, and that the minerals around the fossils show characteristics of being acted on by bacteria. In my opinion it's as the old saying goes; if it looks like a duck... *

As of this writing, the only known smaller and "older" cells than those original complex cells found on Earth have come from space.

Is it really so hard for science to accept the fact that we may not be the center of life in the universe? We know for a fact that water did not originate on Earth. There are icy comets half the size of our planet. If we can come to agree that water has been created elsewhere in the universe, why is it so difficult to think that bacteria might have originated elsewhere also?

Truthfully, with the information known to us, would this not be the most likely scenario?

We have the almost simultaneous formation of the solid planet as we know it, and also the seeding of life. Science has no way of proving/explaining how this happened.

I find it just as likely that a huge icy comet at some point impacted our planet; simultaneously helping to start the cooling effect needed to form solid rock, depositing the original water molecules on the planet, setting the events that would create our atmosphere into motion (through the gases released from the impact), and depositing a simple bacteria onto the planet during the collision.

I believe it may very well be that while life, in the form of early Prokaryotic cells, originated in space... that perhaps Earth was the only place that had the perfect mixture of ingredients to help that original cell evolve into the more complex Eukaryotic cells we see in most higher organisms today.

I believe that the Mitochondria that we see in Eukaryotic cells today might be the evolutionary "fossil" of our ancestors... those original "space bacteria" that seeded our planet billions of years ago.

You may argue that no bacteria would be able to either:

a) be able to survive the entry into the atmosphere,

or

b) that it would not be able to survive the trip through the freezing vacuum of space...

But i would argue that there are known bacteria that happily thrive 5 kilometers under the surface of the Earth in extremely hot volcanic rocks, and that bacteria have been tested and proven to survive 553 days of exposure to space on the outside of the International Space Station! Space Bacteria?

The fact that some Mitochondria can produce energy without oxygen might even be an evolutionary remnant of that long-ago journey our cellular ancestors took.

A lot of science fiction stories have been based off of aliens seeding our planet, and maybe they weren't too far from the truth...

They just might have been off by about 4 billion years.

You know, I was suppose to learn this in biology and it's still confusing to me.

It's like a never ending cycling puzzle going through my brain.

Very interesting, Although I disagree with Earth having what it needs for prokrayotic (Excuse the spelling please) to evolve to eukrayotic, although it probably does.

What I'm saying is I believe it is likely for eukrayotic cells to have come from an outer source, but anythings possible.

Nice presentation. Well put together. I enjoyed your very informative thread.

Well written OP.
Panspermia is the word you may be looking for to describe the movement of life between space bodies.
Ultimately, the life must have originated somewhere.
The likelihood of the complexity being arranged at random is proven impossible, statistically.
Regarding the mitochondrion, this is passed from mother to daughter. Interesting that the criteria for being a Jew is that you must be born of a Jewish mother. Therefore, true Jews technically would have their original mitochondria matched throughout time. Interesting that their criteria would directly relate to this element.

Cool OP. I was expecting a mention of the genome of mitochondria but alas.

I find this interesting.

The endosymbiotic theory concerns the mitochondria, plastids (e.g. chloroplasts), and possibly other organelles of eukaryotic cells. According to this theory, certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts. Mitochondria developed from proteobacteria (in particular, Rickettsiales, the SAR11 clade,[1][2] or close relatives) and chloroplasts from cyanobacteria.

en.wikipedia.org...

Originally posted by Jim Scott
Regarding the mitochondrion, this is passed from mother to daughter.

edit on 1/4/2012 by Jim Scott because: (no reason given)

The resources I have linked to you are more about the ultimate origins of the Mitochondria as a cellular organism and not how the DNA stored there is being passed along in today's animals.

Thank you very much for all the replies so far.

I always loved looking at the time-line of our planet's ultimate formation in college... Sadly, I was too busy at hookah bars to fully appreciate all the information that was at my finger-tips back then.

*Edit for second response*

"Cool OP. I was expecting a mention of the genome of mitochondria but alas.

I find this interesting."

Maybe in a further thread. I am hoping this one doesn't go over too many people's heads for my first post, heh. The one thing I hate about science is how it has a tendency to scare people away right before they get to the best parts.

en.wikipedia.org...

This book describes how a Geneticist has traced mitochondrial dna through the ages back to prehistoric times.

here is a quote from wikipedia

The title of the book comes from one of the principal achievements of mitochondrial genetics, which is the classification of all modern Europeans into seven groups, the mitochondrial haplogroups. Each haplogroup is defined by set of characteristic mutations on the mitochondrial genome, and can be traced along a person's maternal line to a specific prehistoric woman. Sykes refers to these women as "clan mothers", though these women did not all live concurrently. Indeed some "clan mothers" are descended from others (although not maternally). All these women in turn shared a common maternal ancestor, the Mitochondrial Eve.

very good book and with a read if you are interested in this

reply to post by thegoatboy


Yeah we have come a very long way in the tracing of our human roots.

The thing is, our history is a very very short one.

The cells contained in our bodies have existed on Earth in one form or another for over 3 billion years, and I find it fascinating that these topics have never really been explored.

Scientists would rather argue over the evolution from apes instead of looking at what is right in front of their eyes, the evolution from an even earlier form.

Everything on this planet shares a common ancestor in a simple bacteria, and instead of following this trail, they would rather focus on the last 150,000 years and argue over a millionth of the time-line that they should be looking at.

I know how easy it is to get tunnel vision and only focus on finding the origins of our own species, I just find it odd that modern science either:

a) doesn't take the time to fully explore the most obvious evidence in front of them,

or

b) doesn't think the majority of people would take too well to their findings and so keep them to themselves.

Either option would be a travesty in my eyes.

reply to post by thegoatboy


Finished reading through it finally tonight.

Not a bad read. Makes you wonder what those select original "humans" had that made their genes so successful?

reply to post by YouAreLiedTo


Thanks for this thread, I thought it deserved a bump. These little creatures, which ride with us and keep us energized, are just about the best friend humans have.