mitochondrial DNA
THC
Posts: 525
Very interesting stuff...
what do people on here know about it?
seems to be opening up a lot of scientific discussion.....
what do people on here know about it?
seems to be opening up a lot of scientific discussion.....
“Kept in a small bowl, the goldfish will remain small. With more space, the fish can grow double, triple, or quadruple its size.”
-Big Fish
-Big Fish
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mitochondria have dna (hence mitochondralDNA) since they are a living cell / organism. that's all I've got
I've heard it a billion times in those HHMI lectures. But, I didn't retain it, I'm mostly interested in nerve cells and synapses though.
Here is an article from HHMI http://www.hhmi.org/bulletin/may2006/pdf/Mitochondria.pdf
The Powerhouse of the Cell
i should have said that's all i've got in regards to mitochondralDNA. I've got a basic understanding of mitochondria; and I'm happy to keep it at a basic understanding
It's hard to find something on it exactly
Luis Brieba de Castro, a newly named HHMI international research scholar, is working to understand how the DNA that is found outside the nucleus of cells produces proteins. That DNA, called mitochondrial DNA, is found in small cellular structures called mitochondria. Mutations in mitochondrial DNA have been linked to several inherited medical conditions, including some forms of hearing and vision loss.
Scientists know that mitochondrial DNA is inherited only from the mother, but they do not yet fully understand the basic mechanisms of nucleic acid metabolism and how DNA damage is linked to diseases. Brieba de Castro hopes to find answers that could lead to genetic interventions to correct certain inherited disorders. Following previous studies of DNA replication in bacteriophage, a type of virus that infects bacteria, he is working in the yeast Saccharomyces cerevisiae to explore how DNA functions in the mitochondria.
http://www.hhmi.org/news/20061101a.html
There is also something about tracing our ancestry through it.
the stuff about tracing ancestry is the really cool part. i saw a bit on this on 20/20 the other day. Its interesting though...one of their points was that if you go back say 8 generations...of your own DNA...you'd have something like 24,000 grandparents or something crazy. Which means...our genes..are very much a combination of many...many gene pools...from all over the globe.
-Big Fish
So the redneck claim "My mother's my sister" isn't too far off
Doesn't evolution suggest that all species share a common ancestry?
Lucy I'm home!!! mmmm Australopithecusafarensis!
Wait, how many days did it take God to create the universe?
Yes, according to evolution, we all share a distant (very distant as in a long time ago) common ancestor.
Y Chromosomal Adam http://en.wikipedia.org/wiki/Y-chromosomal_Adam
Mitochondria have their own DNA, it is circular in arrangement and similar to that in prokaryotes (bacteria).. It is thought that eukaryotic cells arose from an endosymbiotic relationship between mitochondria and other prokaryotic cells.
There is a distinct evolutionary connection between mitochondrial DNA across species. Additionaly, it is beleived that all human mitochondrial DNA is passed from mother to offspring since egg cells have mitochondria and sperm do not and that all mitochondrial DNA originated from a single female known as mitochondrial Eve.
Anything else you'd like to know?
Just ask
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I was going to point this out....well, SOME of it anyway.:D
Especially your first sentence.
Nuclear fission
The important thing about mitochondiral DNA from out point of view is the way in which it is inherited. We're all taught that our DNA is 50% from our father and 50% from our mother, but that's not exactly true. We get all our mitochondrial DNA from our mothers, because sperm do not contribute any mitochondria when the egg is fertilised. This has applications in forensics etc as well, as mitochnidrial DNA can be used to trace maternal lines. I've noticed that they also like to throw the term 'mitochondrial DNA' randomly into lab scenes on crap shows like CSI and law and order.
-C Addison
That is 50/50 mother/father, correct?
Endocytosis, that is the process whereby a cell membrane absorbs molecules? As in when neurotransmitters are released by the presynaptic cell and absorbed into the receptors of the postsynaptic cell, the process is endocytosis, correct?
Hey!!
That all sounds very interesting Scott and well explained coz even I managed to wrap my head around it.
Aren't mitochondrial dna the little swirly strands?
*~You're IT Bert!~*
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Basically there are two types of cellular organisms on earth - prokaryotic - which are bacteria and archaea. Simple single celled organisms. Very small, with no real structures inside their cells. Basically everything (DNA, proteins, and other molecules) floats around inside the outer cell membrane.
The second type are called eukaryotes. This includes all the higher forms of life, including plants, animals and fungi. Eukaryotic cells (like ours) have structures inside them with their own little membranes, like tiny cells within a cell. These structures are called organelles. The defining ones are the nucleus, which contains most of the DNA, and other things like mitochondria, chloroplasts (only in plants) etc. Some of these organelles have their own DNA. The DNA contained in the nucleus is what you inherit in a 50/50 ratio from your parents. There are two copies of each one of your chromosomes in that nucleus. You get one copy from your mother (these are the ones that were present in the egg cell before fertilisation) and one copy from your father (from the sperm). But since the sperm does not contribute any organelles, the DNA in your mitochondria all comes from your mother.
That's biology 101 for today. I have to go. More later if people are interested.
-C Addison
I'll have to read that several times for it to sink in, but then I have read basically that so many times and it never really sinks in. Mind of a fish! :rolleyes:
Ok so now I have a really dumb question, well the question may not be dumb but my execution of it probably will be.
My understanding of stem cells is that they can make them or are attempting to make them without that bit in the middle that decides what kind of cell they are in order to make them specifically as the kind of cell that they want. Does that mean that the mytochondria and all the other things in the nucleus like the chromosomes would remain? In which case, by having stem cell therapy you would potentially be recieving some one elses DNA? That probably made no sense at all.
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http://www.nytimes.com/library/national/science/012500sci-mitochondrial-dna.html
but the illusion of knowledge.
~Daniel Boorstin
Only a life lived for others is worth living.
~Albert Einstein
I'm pretty sure they replace the nuclear DNA with your own. That was my understanding of how stem cells are created. They incubate an ovary with your DNA instead of the original. The differentiation of stem cells occurs depending on the types of neighbouring cells. Kind of like the way any gene is expressed. The gene doesn't contain an instruction set, but rather it's more complicated. I know that the 'master gene' for a mouse eye can be transmutated into a drosophila (fruit fly) and the drosophila will grow a drosophila eye, instead of a mouse eye, and vise-verca. So the expression of the genes depends on things besides the gene it's self.
But I'm curios to know the answer to your question about mitochondrial DNA as well. And Scott can correct me on the rest if I'm wrong.
Stop by:
http://www.facebook.com/group.php?gid=14678777351&ref=mf
Thanks Ryan. Can't stop now, but I'll be back. I have more questions.
*~You're IT Bert!~*
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So - Following on from what I was saying before, mitochondria are like little bacterial cells that float around inside our cells (which are much larger than a bacterial cell). They are separate from the nucleus and contain their own DNA. In fact, they are so much like bacterial cells that the generally accepted theory on how they came to exist in eukaryotic cells is that back in the days of the primordial slime a large single celled critter probably something like an amoeba tried to eat some smaller bacterial cells by engulfing them. This process is called endocytosis. Rather than being destroyed and absorbed however, the bacterial cells survived inside the larger cell. Somewhere along the line a deal was struck where the bacteria were allowed to live in the favourable environment of the larger cell, in return for chemical energy, which they produced in excess to their own requirements. What we now have is the situation where the symbiotic relationship those ancient bacteria and the larger predatory cell has progressed so far that neither can survive without the other, and they are now infact just different parts of the same organism. Cool hey? Plants made an even better deal somewhere along the line. Not only do they have mitochondria cranking out energy, they also have another type of organelle descended from a photosynthetic bacteria. These are called chloroplasts, and they also have their own DNA, just like mitochondria.
So. . . stem cells. This is a complicated topic, and I need to get back to the lab, but I'll try to explain it just briefly. Ahnimus is kind of correct, but its more complex than that.
Basically the story is that every cell in your body has all the same information stored in the DNA in its nucleus (except red blood cells, but we won't go there). This information is the same regardless of whether its a muscle cell, liver cell, nerve cell, skin cell etc, and it has all the instructions required to make any type of cell in your body. But, even though all those cells contain the same information, its not possible for say, a skin cell to divide and produce a liver cell. Only special types of cells can divide and develop into other cell types. These are called stem cells.
There are several kinds of stem cells, but the ones of most interest to researchers are embryonic stem cells. When an egg is fertilised by a sperm, the fertilised egg (called a zygote) begins to divide. So one cell becomes two, which becomes four, which beomes eight, 16, 32, 64 etc etc. For the first few days after fertilisation, these cells have not yet taken on any particular function. There are no skin cells, no hair follicle cells, no pancreatic cells, just these undifferentiated stem cells. So, if you take the embryo during these first few days (I think between 3 and 5 days is the ideal time), you can extract the stem cells, and start growing them in culture. You can then (in theory) manipulate them to differentiate into whatever kind of cell you like. We're not quite there yet, but the hope is that one day we'll be able to grow new livers, hearts, lungs or whatever outside the body by directing the development of stem cell cultures.
Now, you can get stem cells from a number of sources. There are embryonic stem cells, like I described above, which can only be isolated from an embryo in the very early stages of development. There are also other types of stem cells that can be isolated from placenta and umbilical cord blood, and others that can be isolated from tissue of adults. The difference with these other types compared to embryonic stem cells is that they are limited in the number of other cell types that they can differentiate into.
So, if you want embryonic stem cells, you need an embryo. One way to get one is to fertilise a human egg with a human sperm in a test tube. This is exactly what happens in IVF. Most of the research done so far has used excess embryos produced for IVF. These embryos would have been destroyed anyway, and are donated with the consent of the couple. Another way to get an embryo is to produce one by cloning. This involves taking an unfertilised egg, sucking the nucleus out, and replacing it with the nucleus of another cell from somewhere else. This effectively replaces the 'identity' of that egg cell with that of the cell that nucleus is taken from. The egg now has a full set of two copies of DNA, and can then be tricked into developing. The neat thing about this is that if say, Jeanie, needed a new liver because she drank too much bundy rum, you could take one of her own ova (egg cells), rip out the nucleus, replace it with the nucleus of another cell from her armpit or somewhere, and hey presto! You've got cloned Jeanie stem cells, genetically identical to her. All you have to do then is tell those cells to differentiate into liver cells, grow up a new liver, and transplant it back into her. Because the new liver is genetically identical to her old one, there will be no issues with rejection.
-C Addison
-C Addison
You should read Richard Dawkins 'Anscestor's Tale'. It traces back and attempts to estimate what common anscestors of us and other animal families would be like, and used mDNA and fossil evidence to attempt to date when the anscestor would have existed, while giving lots of insight on how evolution has worked. It's qute interesting, but a bit long and heavy at times. I'm 2/3s of the way done!
My favorite fact so far: Whale's and Dolphin's closest living relitive (still on land): Hippos!
-Ashley Montagu
Thanks scott.
I think this is very much how I understood it from the stem cell scientist guy whose public lecture I went to but I'm too fuzzy atm to hunt out the details or formulate questions.
*~You're IT Bert!~*
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