Image from https://www.newcastle-mitochondria.com/patient-and-public-home-page/what-is-mitochondrial-dna/
Exactly how many
people out there know that the mitochondria, commonly known as the powerhouse
of the cell, contains its own DNA? This tiny organelle in the cytoplasm of the
cell does not just exist to convert
energy from food into energy that can be used by the cells . It
was not until 1963 that scientists discovered DNA in the mitochondria which
was amazing because scientists had thought that DNA only existed in the nucleus
until this point. Mitochondrial DNA accounts for a very tiny fraction of genes,
only 37 of the 20,000 to 25,000 genes to be exact. Even crazier, mitochondrial
DNA is maternally inherited only.
It is unclear as to
why paternal mitochondria get essentially wiped from the cell. According to this
article, there was a recent study
performed on roundworms that showed a self destruct mechanism in the sperm when
it fused with the egg. This study also showed that delaying this self destruct
and allowing paternal mitochondria to exist in the embryo led to low survival
rates. The self destruct mechanism in roundworms arises from a gene called
cps-6 and, if deleted, paternal mitochondria stay around longer in the embryo.
This discovery could help lead scientists to better understand diseases caused
by the mitochondria that lead to blindness, nerve damage, and even dementia.
Since mitochondria
are maternally inherited, it makes it possible to trace maternal ancestries.
Companies like 23andMe use the
mitochondria to do exactly that. This could make it possible to trace all the
way back to what scientists call the "Mitochondrial Eve" who is
considered the woman that all humans inherited their mitochondrial DNA from.
The technology probably does not exist yet to do so but it may be possible in
the future and could answer so many questions. Humans are not the only species
on Earth to maternally inherit mitochondria and this method of tracing ancestry
could be used on many different animals.
The mitochondria may
be famously known as the powerhouse of the cell, however; it is important for
much more. Scientists are still trying to figure out many aspects of the
mitochondria since it is a relatively new area of interest in the world of
biology. Learning more about the mitochondria could be the key behind solving
the many diseases caused by changes or defects in mitochondrial DNA.
-Posted by Brianna Luciani (2)
As you stated in your blog post, mitochondrial DNA is maternally inherited. However, has there ever been cases in which a portion of the father's mitochondrial DNA has appeared inside human cells? From what I could find on the internet, it is very rare for this phenomenon to occur, but it could happen.
ReplyDeletePosted by Lauren Shone
Yes, there have been reported cases of paternal mtDNA found in offspring. Typically, this leads to the offspring not surviving or having diseases related to mtDNA. The article from paragraph two of the post does mention this briefly but, like you, I have also found that it is very rarely occurring.
DeletePosted by Brianna Luciani
I agree, I think mitochondrial DNA can be key to solving many diseases, I do hope this researched is pursued. I have read that mitochondrial related diseases are almost always Fatal, and usually progressive.
ReplyDelete- Fredjah Desmezeaux
I find it very fascinating that companies such as 23andme possibly find even better readings for maternal mitochondrial DNA. It makes me wonder about the mitochondrial cell cycle that we do not learn about in depth. I also wonder how or if mitochondrial DNA differs in humans. Mitochondria themselves are likely more similar to prokaryotic cells due to their lack of a nuclear membrane. Therefore I do not understand how there is any significant difference between maternal and paternal mitochondrial DNA for this reason.
ReplyDeletePosted by Isaac Collibee
In an additional course that I am taking this semester, we have been discussing the molecular and evolutionary history of mitochondria. The endosymbiotic theory states that the evolution of eukaryotic cells originates from prokaryotic organisms. This theory also describes how mitochondria and possibly other organelles (plastids, chloroplasts) represent a formerly free-living prokaryote that was ingested by another. It would be interesting to find some more background information on to how the the mitochondria became maternally inherited.
ReplyDelete-Elise Babula
Mitochondrial DNA is very interesting and it opens many possibilities for developing maternal lineages. This could help evolutionary biologists to study lineages and help to create phylogenies of species. Mitochondrial DNA could also be used to see how related two people are to one another by looking at how much their DNA in the mitochondria has changed. I believe the discovery of mitochondrial DNA led to the Endosymbiotic Theory. This is a theory that explains the origin of eukaryotic life. The theory suggests that a cell engulfed a prokaryotic cell and contained it but did not destroy the cell. This cell, now inside the parent cell was what became the mitochondria. The evidence lies in that the DNA of mitochondria lies within the mitochondria the way DNA lies in many prokaryotic cells. Not in the nucleus that is.
ReplyDeletePosted by John Mariano
Yes, the discovery of mtDNA did lead to the Endosymbiotic Theory. This is also a theory that scientists have used to discover how chloroplasts became organelles in plants. You are exactly right in your description of the theory and I agree that mtDNA is incredibly interesting. I can't wait to see where scientists take this research in the future.
DeletePosted by Brianna Luciani