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mitochondria independent organism?

slo1
Posts: 5,199
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2/19/2016 1:40:10 AM
Posted: 1 year ago
http://www.sciencemag.org...

Scientists think that mitochondria were once independent single-celled organisms until, more than a billion years ago, they were swallowed by larger cells. Instead of being digested, they settled down and developed a mutually beneficial relationship developed with their hosts that eventually enabled the rise of more complex life, like today"s plants and animals.
Axonly
Posts: 2,543
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2/19/2016 2:25:38 AM
Posted: 1 year ago
At 2/19/2016 1:40:10 AM, slo1 wrote:
http://www.sciencemag.org...

Scientists think that mitochondria were once independent single-celled organisms until, more than a billion years ago, they were swallowed by larger cells. Instead of being digested, they settled down and developed a mutually beneficial relationship developed with their hosts that eventually enabled the rise of more complex life, like today"s plants and animals.

Ah, someone with something interesting to say. This theory is more broadly known as "Symbiogenesis", its a theory that explains how Eukaryotic cells originated from Prokaryotes, it is believed that mitochondria originated from some sort of Proteobacteria. Mitochondria aren't unique in this situation, as it is also believed that chloroplasts underwent a similar process, except from cyanobacteria.

Then a creationist comes along and says "No! They came from God!"
"Hate begets hate"
Skepsikyma
Posts: 9,274
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2/19/2016 4:59:32 AM
Posted: 1 year ago
At 2/19/2016 1:40:10 AM, slo1 wrote:
http://www.sciencemag.org...

Scientists think that mitochondria were once independent single-celled organisms until, more than a billion years ago, they were swallowed by larger cells. Instead of being digested, they settled down and developed a mutually beneficial relationship developed with their hosts that eventually enabled the rise of more complex life, like today"s plants and animals.

Yeah, it's a common theory about the origin of double-membrane bound organelles, and makes a lot of sense. Life is fascinating.
"See now Oblivion shimmering all around us, its very tranquility deadlier than tempest. How little all our keels have troubled it."
- Lord Dunsany -

"Over her head the stars, the thoughts of God in the heavens,
Shone on the eyes of man, who had ceased to marvel and worship"
- Henry Longfellow -

Virtutem videant intabescantque relicta
keithprosser
Posts: 4,634
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2/19/2016 6:26:53 AM
Posted: 1 year ago
I have no basis to confirm this speculation about mitochondria, but, based on what I do know, it wouldn't surprise me if the evidence bore this out.

With the regular caveats that apply to scientific facts the independent origin of mitochondria has been orthodoxy for decades.

Mitochondria are mini-cells found within the sort of 'regular' cells people are more familiar with. Mitochondria are enclosed in their own cell walls and have their own DNA so they really are like little single cell organisms living inside larger cells. The enclosing cells use them for producing energy more efficiently than a cell without mitochondria could.

Cells without mitochondria (prokaryotic cells) do exist, but they only form boring single-cell organisms. Complex multi-cell organisms are made of the energy-efficient cells with mitochondria (eukaryotic cells), so how cells got their mitochondria is an important question from the point of view of the history of life.

Mitochondria could have appeared by 'budding off' from the cells regular nucleus, but mitchondria look and act so much like indepedent organims that it seems almost certain that is what they were. At some point in time - about a billion years ago - a large prokaryotic cells engulfed a smaller prokaryotic cell and the smaller cell not only survived but ttok permanent resisdence.

Probably! Of course there are other hypotheses, but the 'endosymbiotic' theory has stood up to several decades of being examined and tested, so it is (as I said) orthodox science these days.

The article is about the rate and mechanisms behind how genes transferred from the mitochondial parasite to the regular nucleus of the host over time. To quote:

"Over the years, the mitochondrial genome has shrunk. The nucleus now harbors the vast majority of the cell"s genetic material"even genes that help the mitochondria function. In humans, for instance, the mitochondrial genome contains just 37 genes, versus the nucleus"s 20,000-plus."
keithprosser
Posts: 4,634
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2/19/2016 7:52:51 AM
Posted: 1 year ago
The living cell is one of the most amazing things I know of. What goes on in each and every cell of our bodies 24 hours a day is breath-taking. I recommend Drew Berry's animations of cell function on Youtube - much more fun than reading about it!