Monday, October 26, 2020
Mitochondrial Health

Mitochondrial DNA inheritance pattern

Mitochondrial DNA inheritance pattern – lecture explains about cytoplasmic inheritance or maternal inheritance pattern.
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In most multicellular organisms, mtDNA is inherited from the mother (maternally inherited). Mechanisms for this include simple dilution (an egg contains 100,000 to 1,000,000 mtDNA molecules, whereas a sperm contains only 100 to 1000), degradation of sperm mtDNA in the fertilized egg, and, at least in a few organisms, failure of sperm mtDNA to enter the egg. Whatever the mechanism, this single parent (uniparental) pattern of mtDNA inheritance is found in most animals, most plants and in fungi as well.
Female inheritance

In sexual reproduction, mitochondria are normally inherited exclusively from the mother. The mitochondria in mammalian sperm are usually destroyed by the egg cell after fertilization. Also, most mitochondria are present at the base of the sperm’s tail, which is used for propelling the sperm cells. Sometimes the tail is lost during fertilization. In 1999 it was reported that paternal sperm mitochondria (containing mtDNA) are marked with ubiquitin to select them for later destruction inside the embryo.[5] Some in vitro fertilization techniques, particularly injecting a sperm into an oocyte, may interfere with this.

The fact that mitochondrial DNA is maternally inherited enables researchers to trace maternal lineage far back in time. (Y-chromosomal DNA, paternally inherited, is used in an analogous way to trace the agnate lineage.) This is accomplished on human mitochondrial DNA by sequencing one or more of the hypervariable control regions (HVR1 or HVR2) of the mitochondrial DNA, as with a genealogical DNA test. HVR1 consists of about 440 base pairs. These 440 base pairs are then compared to the control regions of other individuals (either specific people or subjects in a database) to determine maternal lineage. Most often, the comparison is made to the revised Cambridge Reference Sequence. Vilà et al. have published studies tracing the matrilineal descent of domestic dogs to wolves.[6] The concept of the Mitochondrial Eve is based on the same type of analysis, attempting to discover the origin of humanity by tracking the lineage back in time.

Because mtDNA is not highly conserved and has a rapid mutation rate, it is useful for studying the evolutionary relationships – phylogeny – of organisms. Biologists can determine and then compare mtDNA sequences among different species and use the comparisons to build an evolutionary tree for the species examined.

Because mtDNA is transmitted from mother to child (both male and female), it can be a useful tool in genealogical research into a person’s maternal line.
Male inheritance
Main article: Paternal mtDNA transmission

It has been reported that mitochondria can occasionally be inherited from the father in some species such as mussels.[7][8] Paternally inherited mitochondria have additionally been reported in some insects such as fruit flies,[9] honeybees,[10] and periodical cicadas.[11]

Evidence supports rare instances of male mitochondrial inheritance in some mammals as well. Specifically, documented occurrences exist for mice,[12][13] where the male-inherited mitochondria was subsequently rejected. It has also been found in sheep,[14] and in cloned cattle.[15] It has been found in a single case in a human male.[16]

While many of these cases involve cloned embryos or subsequent rejection of the paternal mitochondria, others document in vivo inheritance and persistence under lab conditions.
Source of the article published in description is Wikipedia. I am sharing their material. © by original content developers of Wikipedia.


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20 thoughts on “Mitochondrial DNA inheritance pattern
  1. It's an oversimplification to say we get nuclear DNA from all of our ancestors, since, as an example, whether or not I inherited any nuclear DNA from my mother's paternal grandmother, would depend on which bit of DNA my mum's paternal grandmother happened to pass to my mum's father, in turn which bits of her DNA he then passed on to my mother, and which remaining bits of my great-grandmother's DNA (if any) made the cut again when my mum passed DNA onto me. Put more simply some ancestors, even at the closely related level in the diagram, may, by sheer randomness of the inheritance, not pass anything down as far as us. The more generations we go back the less likely it is that we inherited any nucelar DNA from any specific ancestor on that generation.

  2. I find this very interesting because my Mum, me and my Daughter and her daughter look very similar at the same age especially at the younger years. I have found an old photo of my Mother's Mother in her old age and I seem to looking more like her as I age.

  3. I have a chronic fatigue illness and I've wondered if my mitochondria is somehow afflicted. Maternal inheritance makes sense in that my mother had similar issues. Also my mother's side of the family has autoimmune diseases such as MS and rheumatoid arthritis.

  4. Furthermore, all humans have mtDNA from one of three haplogroups L,M,N. The region of intersection is southwest Asia. The reason is because all humans have mtDNA from one of the three daughters-in-law of Noah.

  5. If you are a geneticist, would you kindly explain….I think the way it works is that it is better to have a male sibling take the test because you would get the results from both parents. If you are female you are only going to get your female ancestors heritage, but not your male ancestors. You are really only going to get a quarter of what you are. Am I right? Thanks if you can help.

  6. How does MtDNA change? For example, my mothers dna result showed different countries. How does the DNA show different countries if it doesn’t change when getting passed down from mother to daughter?

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