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joexjoe t1_iv0s1o2 wrote

Reply to comment by scottish_beekeeper in Why don't we have Neandertal mitochondrial DNA? by nodeciapalabras

To add.. The egg has mitochondria thus mdna inside. The sperm has it only in its tail. 99.9% of the time just the head gets inside the egg during fertilzation thus no paternal mdna is passed on.

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LeftToaster t1_iv1uvtj wrote

This (only the head of the sperm enters the ovum) was once thought to be true but it is now known that the entire sperm cell, including the mitochondria and flagellum, enters the egg at fertilization.

Misconceptions about mitochondria ...

Nature - eliminating paternal mitochondrial dna

The egg contains over 100,000 mitochondria while the sperm contains 50 - 75. This could mean that the paternal mtDNA are either diluted out of the embryo or eliminated early in oocyte development.

The first paper suggests the paternal mtDNA could simply be diluted beyond detection:

>We simply do not yet know what happens to the paternal contribution of mtDNA in humans, but the simplest explanation is that it is diluted beyond recognition by researchers using relatively low resolution techniques of molecular biology.

The second one suggests elimination of the paternal mtDNA

>In mammals, the inheritance of mitochondrion and its DNA (mtDNA) is strictly maternal, despite the fact that a sperm can inject up to 100 functional mitochondria into the oocyte during fertilization. The mechanisms responsible for the elimination of the paternal mitochondria remain largely unknown.

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joexjoe t1_iv2ylr0 wrote

Wow thanks. I am already out of date, I learned that in genetics in college!

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ScienceMomCO t1_iv3fubh wrote

Just to clarify (because I’m a teacher):

mDNA = messenger DNA

mtDNA = mitochondrial DNA

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