Mitochondria
- Thread starter timojin
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No. Not anymore. Most of their genes have been transferred to the cell nucleus.
Huh? My understanding is that mitochondria have their own genome, I have never heard that a mitochondria's genes have been transferred to the cell nucleus, I don't even know what that is suppose to mean.
No they cannot. LINK
Yazata
Valued Senior Member
It only has 37 genes, many of them concerned with energy metabolism, which mitochondria spend their time doing.
Most of the proteins found in mitochondria are coded for by genes found in the cell nucleus.
But assuming the the endosymbiotic theory of mitochondrial origins is correct and they are descended from very ancient free-living bacteria, the genes responsible for all of their proteins must at one time have been located in the mitochondrion's ancestral bacterial genome.
https://en.wikipedia.org/wiki/Mitochondrial_DNA
"In the cells of extant organisms, the vast majority of the proteins present in the mitochondria (numbering approximately 1500 different types in mammals) are coded for by nuclear DNA, but the genes for some of them, if not most, are thought to have originally been of bacterial origin, having since been transferred to the eukaryotic nucleus during evolution." https://en.wikipedia.org/wiki/Mitochondrial_DNA
You are right and I was wrong. Thanks for making me go and do a bit of research, fascinating stuff.
Question: as far proteines,would be correct in saying many proteines in bacteria are found in higher form of life, example I will assume there will be some albumine in bacteria, if there is, so higher form of animals have , I suppose lysozyme will be present ete. ete.
Something similar happened to make chloroplasts from prokaryotic-photosynthetic algae:
Over time, the cyanobacterium was assimilated, and many of its genes were lost or transferred to the nucleus of the host.[16] Some of its proteins were then synthesized in the cytoplasm of the host cell, and imported back into the chloroplast. https://en.wikipedia.org/wiki/Chloroplast
If the mitochondria have transferred most of their genes to the nucleus DNA, via evolution, why do they retain any DNA, since the nucleus could do it all?
In other words, say we assume the mitochondria started out as having all the genes that are needed to be self sufficient. Through evolution, little by little, genes are transferred to the nucleus DNA of the host. If we extrapolate that, why not transfer all the DNA to the nucleus? Why did it retain a small share of genes? What would happen if and when all the genes are transferred (extrapolation of this theory)?
In other words, say we assume the mitochondria started out as having all the genes that are needed to be self sufficient. Through evolution, little by little, genes are transferred to the nucleus DNA of the host. If we extrapolate that, why not transfer all the DNA to the nucleus? Why did it retain a small share of genes? What would happen if and when all the genes are transferred (extrapolation of this theory)?
Yazata
Valued Senior Member
Do we know that? Or does the mitochondrion retain genes for functions that aren't coded for in the nucleus?
I'm not sure that genes and their DNA actually physically moved from the mitochondrion to the nucleus and were effectively cut-and-pasted from one to the other. Perhaps the nucleus already had many of the same genes, or close analogues of them. If the nuclear genes were more efficient at expressing themselves, the mitochondrial genes might have been rendered superfluous. That still doesn't explain why these hypothetical superfluous mitochondrial genes eventually dissappeared. (Genomes are like basements full of old forgotten stuff, which is why evolutionary biologists like to poke around in them.) Perhaps the mitochondrial ancestor didn't have the same kind of DNA repair machinery as the nucleus so that anything that could break without loss of function eventually did.
It's a good question. I'll speculate that perhaps the mitochondrion had some genes that the nucleus didn't have that were vital to its energy-metabolism function. (If the mitochondrion wasn't better than the host cell in doing that, it would have been a parasite rather than a symbiont.) Losing those unique specialized genes might have resulted in mitochondrial diseases that would have dramatically lowered evolutionary fitness. So evolution would preserve them, just as some of the most vital regions of nuclear DNA are highly preserved and remain virtually identical in diverse taxonomic classes.
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If the mitochondria were left with no genes it would not do anything, so it would be useless. I would imagine that the genes that the mitochondria transferred or lost because they were no longer needed are taken over by the cell because it is more efficient for the cell to produce the proteins than the mitochondria. That leaves the mitochondria free to concentrate on the it's main jobs. A very nice symbiotic relationship.
danshawen
Valued Senior Member
http://www.targeting-mitochondria.com
Not a link to an answer, but this looks like an interesting symposium on the subject for anyone interested.
Like Lucas' fictional Jedi and Sith midi-chlorians, you get your mitochondrial genes only from your biological mother. This suggests that mitochondria are so old, they actually predate the origins of sexual reproduction. Not a likely candidate for any independent organism that is in evolutionary terms very far North of a nematode.
Not a link to an answer, but this looks like an interesting symposium on the subject for anyone interested.
Like Lucas' fictional Jedi and Sith midi-chlorians, you get your mitochondrial genes only from your biological mother. This suggests that mitochondria are so old, they actually predate the origins of sexual reproduction. Not a likely candidate for any independent organism that is in evolutionary terms very far North of a nematode.
It is believed that the mitochondria of plants and animals are from the same source; i.e that it was a 'modern' eukaryote with a mitochondria that engulfed a prokaryotic algal cell to form the first eukaryotic plant.
Because mitochondria are passed through the ovum, and not incorporated in sperm, it is possible to trace ancestry through mitochondria, allowing for us to estimate when Mitochondrial "Eve" lived, the mother of all living people. https://en.wikipedia.org/wiki/Mitochondrial_Eve
I had the impression the tail of the sperm have or is composed of mitochondria , because of the need of large amount of energy to propel and swim . Then the question remains : in the fertilization does the tail remain outside of the ovim or it gets into the ovum ?
EDIT: You are correct the mitochondria are located at the tail base (sperm midsections]
What do you mean the question remains, isn't this is the first time you asked it? Anyway, any mitochondria from the father that make it into the egg are destroyed by egg cell after it is fertilized.
EDIT: In general mitochondria in human from the father will not make it into the egg cell because the tail does drop off. Any that do make it into the fertilized egg are apparently destroyed.
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[QUOTE="origin, post: 3318364, member: 143078"
Anyway, any mitochondria from the father that make it into the egg are destroyed by egg cell after it is fertilized.[/QUOTE]
Interesting : fathers and mothers mitochondria must have different receptors to be identified as foreign body to be lysed by some ovom enzyme,
Anyway, any mitochondria from the father that make it into the egg are destroyed by egg cell after it is fertilized.[/QUOTE]
Interesting : fathers and mothers mitochondria must have different receptors to be identified as foreign body to be lysed by some ovom enzyme,
I know very little about biology, which is ironic since my daughter just graduated with a molecular genetics degree, but the info I got on paternal mitochondria is just from wiki.
Here is the wiki link.
Thank you. I am not a biologist . It was a curiosity question. Reading the link it opens more questions .