Question
Asked 11th Apr, 2018
  • University of Anbar, College of Medicine

Why mitochondrial DNA is inherited from mother only in contrast with nuclear DNA which inherited from both of parents (dad and mom)?

Mitochondria are structures within cells that convert the energy from food into a form that cells can use. Although most DNA is packaged in chromosomes within the nucleus, mitochondria also have a small amount of their own DNA. This genetic material is known as mitochondrial DNA or mtDNA. In humans, mitochondrial DNA spans about 16,500 DNA building blocks (base pairs), representing a small fraction of the total DNA in cells.
Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function. Thirteen of these genes provide instructions for making enzymes involved in oxidative phosphorylation. Oxidative phosphorylation is a process that uses oxygen and simple sugars to create adenosine triphosphate (ATP), the cell's main energy source. The remaining genes provide instructions for making molecules called transfer RNA (tRNA) and ribosomal RNA (rRNA), which are chemical cousins of DNA. These types of RNA help assemble protein building blocks (amino acids) into functioning proteins.

Most recent answer

17th Apr, 2020
Grace Tambo
Matopos Research Institute
The mitochondria in the sperm cell self destructs after fertilization because it becomes lethal

Popular Answers (1)

12th Apr, 2018
Jessica Furriol-Palmer
HelseVest
Briefly, if you refer to human mitochondria, the most accepted hypothesis is that only the head and part of the neck of the spermatozoon enters the egg in the fertilization. The head is mainly composed by a compact nucleus and a very small cytoplasm. After the neck, the middle piece is found: here lie paternal mitochondria, which do not enter the egg, avoiding paternal mitochondria inheritance.
From an ecological point of view, the strategy of spermatozoa is to produce a lot of gametes with the minimum cost (reducing size and removing/modifying non-useful organelles) and try to improve the probability of fertilize an egg. In the case of the egg cells, only few are produce with a big cost. They are big (0.15-0.20um) and provide with all the cellular machinery and nutrients needed for the zygote, which includes mitochondria.
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All Answers (28)

11th Apr, 2018
Dominik Funken
Hannover Medical School
The mitochondria in human 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. However, some in vitro techniques like injecting a whole sperm into the egg cell might interfere with this.
2 Recommendations
11th Apr, 2018
Math Geurts
University of Amsterdam
I believe it is still a bit controversial. But the main explanation for this maternal-uniparental inheritance is that in sexual reproduction, the mtDNA from the father is simply lost: most of the mitochondria of the sperm cell is present in the sperm's tail, and this tail is lost when the sperm cell enters the oocyte, in other words when the fertilization starts.
Source: Russell, iGenetics, 3rd ed.
I believe the same counts for the chloroplast genes, which have also a part of own DNA. But that counts for plants.
2 Recommendations
11th Apr, 2018
Dominique Liger
Université Paris-Sud 11
Hi there,
In sexual reproduction, male gamete only contributes to the nuclear genome in the fertilized egg.
1 Recommendation
11th Apr, 2018
Herve Levesque
Lycée JP Vernant, Sèvres (92, France) ; Ifé-ENS de Lyon
This is not a general rule since biparental inheritance both for mitochondria and chloroplasts is frequently observed in plants
2 Recommendations
11th Apr, 2018
Katie A Burnette
University of California, Riverside
Are you interested in the biochemical mechanism for HOW mitochondrial DNA in only maternally inherited (at least for most organisms, there are notable exceptions)? Or are you more interested in the evolutionary WHY of the observed uni-parental inheritance?
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12th Apr, 2018
Sagar Swami
CSIR - National Chemical Laboratory, Pune
In sexual reproduction, during the course of fertilization event only nuclear DNA is transferred to the egg cell while rest all other things destroyed.And this is the reason which proves that Mitochondrial DNA inherited from mother only.
Doubly uniparental inheritance of mtDNA is observed in bivalve mollusks while Male mitochondrial inheritance was recently discovered in Plymouth Rock chickens. So here are the examples which shown exceptions to this rule.
If want to know more just google aboutDoubly uniparental inheritance,and Male mitochondrial inheritance.
1 Recommendation
12th Apr, 2018
Jessica Furriol-Palmer
HelseVest
Briefly, if you refer to human mitochondria, the most accepted hypothesis is that only the head and part of the neck of the spermatozoon enters the egg in the fertilization. The head is mainly composed by a compact nucleus and a very small cytoplasm. After the neck, the middle piece is found: here lie paternal mitochondria, which do not enter the egg, avoiding paternal mitochondria inheritance.
From an ecological point of view, the strategy of spermatozoa is to produce a lot of gametes with the minimum cost (reducing size and removing/modifying non-useful organelles) and try to improve the probability of fertilize an egg. In the case of the egg cells, only few are produce with a big cost. They are big (0.15-0.20um) and provide with all the cellular machinery and nutrients needed for the zygote, which includes mitochondria.
11 Recommendations
13th Apr, 2018
Joseph Ogbede
University of British Columbia - Vancouver
The mitochondria in sperm cells are lost during fertilization, hence the zygote only inherit the mitochondria from the egg.
1 Recommendation
13th Apr, 2018
Anna Maria Labecka
Jagiellonian University
In androgenetic Corbicula clams, spermatozoa are unreduced and the maternal nuclear chromosomes are extruded as two polar bodies. The offspring inherit only the paternal nuclear genome but mitochondria have typical "motherly" origin.
Best regards, Ania
3 Recommendations
16th Apr, 2018
Norma Karina Hernández-Ibarra
Centro Interdisciplinario de Ciencias Marinas Instituto Politécnico Nacional
Large structures called autophagosomes, are known to engulf paternal mitochondria shortly after a sperm penetrates an egg.
2 Recommendations
29th Sep, 2018
Jai Ghosh
Smt. K. W. College Sangli 416416. Maharashtra. INDIA
The answer is very simple. In humans nuclear DNA is 46 in number distributed in 23 pairs. Therefore, 23 of these comes from mom and 23 comes from the so called "dad". While mitochondria is having only one chromosome and mitochondria is not found in sperm. Therefore, the only donor will be mom.
1 Recommendation
29th Sep, 2018
John - Collins
Helmholtz Centre for Infection Research- HZI (1975- 2005, GBF); Prof TU Braunschweig 1986-2010
Could someone give a proper peer- reviewed reference for whether or not the sperm mitochondria are excluded from entering the egg or are destroyed after entering
29th Sep, 2018
Herve Levesque
Lycée JP Vernant, Sèvres (92, France) ; Ifé-ENS de Lyon
Jai, the above discussion mentioned the fact that mitochondria are found in sperm. So John repositioned the question "whether or not the sperm mitochondria are excluded from entering the egg or are destroyed after entering". Among several others, an interesting response is those of Norma Karina but the reference for that point is missing! It would be very appreciated. A second point, Jay, is the status of chromosome in mitochondria : they are numereous, and recombination and heteroplasmy have been clearly established especially in plants, so we cannot say there is only one chromosome.
29th Sep, 2018
Jai Ghosh
Smt. K. W. College Sangli 416416. Maharashtra. INDIA
You may read the attached paper: In fact this questions has been aptly answered by geneticists at Stanford University.
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29th Sep, 2018
Herve Levesque
Lycée JP Vernant, Sèvres (92, France) ; Ifé-ENS de Lyon
Thank you Jay for the reference, a paper I do not know.
1st Oct, 2018
Surendra Katyare
Center for Innovation in Nutrition, Health & Disease, IRSHA, BVU, Pune
Because only the head of spermatozoa enters the ovum. The middle piece-sarcomere- which contains mitochjondria (to give motility) does not enter the ovum. Thus the ferilized ovum has mitochondria only from the ovum i.e. mother.
1 Recommendation
2nd Oct, 2018
Tamotsu Hashimoto-Gotoh
Kyoto Prefectural University of Medicine
I just thought this is the problem of statistic probability. If only few copies of paternal mitocondorion can enter into an egg in which a few thousand of maternal copies exist, the probabiity of selecting paternal copies as template may be ca. 1/1000, so that after ten time cell division patarnal copies may be lost 1/10∨30, namely eventually nothing.
2 Recommendations
13th Feb, 2019
Maurice Ekpenyong
University of Calabar
I strongly agree with Tamotsu and Jai. It is all a matter of statistical proportions. 1:1000 (paternal to maternal mitochondrial ratio). In a few cell division cycles, paternal mitochondrial content is as good as lost and therefore irrelevant in mitochondrial gene expressions. And Jai, your attached paper is phenomenal. Thank you.
13th Feb, 2019
Luis Monteagudo
University of Zaragoza
Some cases of paternal mitochondrial inheritance (conserving these mitochondria for up to three generations) have been recently reported. As in classical mutation analysis, this may lead to a better understanding of the usual way to kpreserve only maternal mitochondria
1 Recommendation
18th May, 2019
Santosh Singh
Punjabi University, Patiala
In ferilization process sperm donates only nucleus and centrioles to egg. Nucleus contains 23 chromosome while centriole contains only cytoskeleton. other organelles like Mithochondria, do already present in egg so it continue persist in Zygote. so only mother cell gamete i.e. egg play role in Mitochondrial inheritance.
1 Recommendation
14th Mar, 2020
Farid Elasmer
Ain Shams University
Could it be that mitochondria in the sperms is only needed to supply energy for a highly active mobile sperm . After fertilization there is no need for a fertilized stationary egg.
14th Mar, 2020
Herve Levesque
Lycée JP Vernant, Sèvres (92, France) ; Ifé-ENS de Lyon
The fertilized egg is not static since it moves in the fallopian tube. The mobility being mainly due to epidermal cilia of the uterus
15th Mar, 2020
Farid Elasmer
Ain Shams University
May be the mitochondria in the sperms is needed for mobile structure. After oralfertilization which have it's own mitochondria and
15th Mar, 2020
Farid Elasmer
Ain Shams University
Sperms need mitochondria because they are active mobile elements. After ova fertilization which is immobile, there will be need for the extra mito. Comming from sperm. Could it be true?
15th Mar, 2020
Farid Elasmer
Ain Shams University
1it is the cilia of the uterus which drives the movement and no need for extra mito. It has to be researched
15th Mar, 2020
Herve Levesque
Lycée JP Vernant, Sèvres (92, France) ; Ifé-ENS de Lyon
You are right. I would like to correct the formulation static or immobile ova since it moves. Your energetic consideration about sperm motility is very correct! Thanks
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