Did you know that you only inherit DNA from your mother? Mitochondrial DNA

Did you know that you only inherit DNA from your mother? Mitochondrial DNA

Do you think you inherit all of your DNA from your parents? In fact, there is mitochondrial DNA that is only inherited from the mother.
This article describes the difference between mitochondrial and nuclear DNA.

Knowledge of DNA helps you choose

Do you have no knowledge of DNA but are interested in gene therapy or genetic testing?
For these individuals, knowledge of DNA is helpful.
This is because DNA knowledge can help us determine which tests and treatments are best for us.

This article explains [the difference between mitochondrial DNA and nuclear DNA].

Without knowledge of DNA, you cannot make your own decisions and choose your own treatments and tests.
If this happens, you run the risk of being forced to undergo treatments and tests that you do not need, costing you valuable time and money.
However, with the knowledge of DNA you will be able to make your own testing and treatment choices.
The result,

  • The diet that works best for you
  • Indicators for the future of the baby before it is born.
  • How to prevent you from getting sick
  • If you are sick, the best treatment

and you may get the information you want to know.
The knowledge in this article could be one of those articles that helps you make your own choices and decisions.

Difference between mitochondrial DNA and nuclear DNA

1. different places of existence, shapes and sizes

Mitochondrial DNA is in the mitochondria, nuclear DNA is in the nucleus.

The nucleus and mitochondria are located in the cell.
The cells are

  • hair (head)
  • internal organs
  • Body fluids and blood
  • bone
  • skin
  • sperm
  • ovum

and others, which build the human body.
In other words, DNA is found in the cell, but there are two types of DNA in the cell: mitochondrial DNA and nuclear DNA.

Mitochondria and their respective DNA

Shape and length of mitochondrial and nuclear DNA

The shape of the DNA is also different.
Mitochondrial DNA is circular double-stranded and nuclear DNA is linear double-stranded.

Cyclic and linear

And there are differences in length,

  • Mitochondrial DNA is about 16,000 base pairs
  • Nuclear DNA is 3 billion base pairs

A base pair is a unit of length of DNA.

Bases are one of the components of DNA,

  • Adenine (A)
  • Cytosine (C)
  • Chimin(T)
  • Guanine (G)

is called a base.
DNA is a substance consisting of four bases randomly arranged and connected.
Furthermore, bases are attached to bases, forming a double helix.
Since the bases exist in pairs, they are called base pairs.
For example, if a DNA with the bases (C)(G)(A)(C)(T) exists, it is a 5-base DNA.
Each base has a specific pair of bases,

  • Adenine (A) and Thymine (T)
  • Guanine (G) and cytosine (C)

is a paired base, so (G)(C)(T)(G)(A) is attached to form a double helix.
This double helix DNA takes the form of a circular double strand or linear double strand.

double helix DNA

Why are there two types of DNA in a cell?

It is said that this is because the ancestors of mitochondria originally entered the cell and coexisted (intracellular symbiosis theory).
The role of mitochondria is to convert harmful oxygen into energy that can be used by cells.
In other words, without mitochondria, cells are less likely to obtain energy from oxygen.
Thanks to the ancestors of mitochondria living in cells, efficient energy metabolism is now possible.

2. different ways of being inherited.

DNA is inherited equally from both parents, this is nuclear DNA.
Mitochondrial DNA is thought to be inherited only from the mother.
The reason is that when fertilization*1 occurs, the mitochondrial DNA in the sperm is deleted.
It is not known why mitochondrial DNA is deleted in humans.
In C. elegans, as in humans, the paternal mitochondrial DNA is deleted.
In C. elegans, however, deletion of mitochondrial DNA is thought to involve autophagy*2.

※2Autophagy: the ability to break down and recycle materials that are no longer needed in the cell. It is a cellular function and has been confirmed in humans; famous for the 2016 Nobel Prize in Physiology, Yoshinori Osumi's research.
※1Fertilization: Fertilization occurs when a sperm enters an egg. Both sperm and egg are cells and have nuclear and mitochondrial DNA.

3. transcription and translation are in different places

Transcription and translation of mitochondrial DNA take place within the mitochondria.
However, in nuclear DNA, transcription is in the nucleus and translation is in the cytoplasm.

What is transcription and translation?

Transcription and translation are the processes of making proteins from DNA.
In other words, DNA is transcribed and translated, and thus proteins are produced.
For the sake of clarity, DNA can be likened to a dictionary.
Recorded in the dictionary is a protein blueprint.
The explanation then is that transcription is 'copying the necessary pages from a dictionary.
Proteins recorded in DNA are not always produced.
The basic principle is that they are made when they are needed and in the amount needed.
Translation is the process by which the human body makes proteins from blueprints from which only the necessary pages have been copied (transcribed).

4. DNA is used differently.

It is estimated that mitochondrial DNA is used about 93% of the time and nuclear DNA about 5%.
DNA utilization frequency is the percentage of protein blueprints contained in the DNA.
For example, 5% of nuclear DNA indicates that 5% of the protein blueprint is written in the dictionary.
If the dictionary has 1000 pages, 50 of them are protein blueprints.

Intergenic regions are the regions that are not the blueprints of proteins.

DNA is divided into gene regions and intergenic regions.
The gene region (gene) is the blueprint of the protein.
Intergenic regions include those parts of the blueprint that have been rewritten or lost due to mutation or other reasons.
In addition, intergenic regions also play a role in coordinating gene regions.
For example, suppose that a gene region (gene) makes a protein and supplies it to the body through transcription and translation.
The body is now filled with the supplied protein and no longer needs protein.
In this case, the intergenic region coordinates to prevent the gene region from producing proteins.

5. Different number of copies

It is said that there are two nuclear DNAs and 100-2000 mitochondrial DNAs.
The reason for the large number of copies of mitochondrial DNA is that mitochondria divide and multiply within the cell.

6. the probability of mutations occurring is different.

The probability of mutation is 5 to 10 times higher for mitochondrial DNA.
Looking at how much difference there is in the DNA of humans and chimpanzees,

  • Nuclear DNA is about 1%.
  • Mitochondrial DNA is about 9%.

It is believed that humans and chimpanzees diverged from the same ancestor.
The difference between humans and chimpanzees is greater for mitochondrial DNA, even though the time period during which mutations occur is the same.
In other words, mitochondrial DNA is more frequently mutated than nuclear DNA.

Mitochondrial DNA is prone to mutation by its own reactive oxygen species.

The reason mitochondrial DNA is prone to mutation is reactive oxygen species.
It is believed that mitochondrial DNA is more susceptible to the effects of reactive oxygen species than nuclear DNA.
This is because mitochondria produce reactive oxygen species themselves.
While reactive oxygen species (ROS) play a role in immune function and infection defense, an excess of ROS is believed to lead to aging and cancer.
Mitochondria make energy from oxygen.
However, a byproduct of this process is the production of reactive oxygen species.
Reactive oxygen species damage DNA, causing base substitutions, leading to mutations.

Base substitution is one of the causes of mutation

Base substitution is a phenomenon in which one or more parts of DNA are changed.
DNA was a substance consisting of four bases randomly arranged and connected, right?
For example, suppose the line is (A)(C)(C)(G)(G)(G).
If one base substitution were to occur, it would be (T)(C)(C)(G)(G)(G), with the first letter (A) and (T) interchanged.
When base substitutions occur, DNA, the blueprint for proteins, is altered, potentially causing adverse effects on the body.
This is because in some cases, when the blueprint changes, different proteins are produced or no proteins are produced.
As an example of an adverse effect, mutations in mitochondrial DNA can cause "mitochondrial disease," which can lead to skeletal muscle and brain damage.
Furthermore, it is believed to be closely related to the development of diabetes and the severity of cancer.

...mutations that allowed us to evolve.

Do you have a bad impression of mutation because it messes up the protein blueprint?
But it is not all bad.
Because if it works in the right direction, it will help the survival of the species as evolution.
For example, it was said that humans and chimpanzees have the same ancestors, right?
It is believed that mutations occurred in response to changes in the environment, leading to the divergence of humans and chimpanzees.

7. Different usage methods

Nuclear DNA is
Looking at how much difference there is in the DNA of humans and chimpanzees,

  • prenatal diagnosis
  • paternity test
  • PCR test
  • Forensics of Crime
  • gene therapy

The product will be used for the following purposes

In addition, it is used for aging research.
It has been suggested that mutations in mitochondrial DNA can lead to aging if mitochondrial function is impaired.
Mitochondrial dysfunction directly leads to a decrease in body energy,

  • Lower physical activity.
  • Decreased internal organ function
  • The body is less likely to produce enzymes.

and other characteristics of aging will appear on the surface.