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| Figure 1: Mitochondrial DNA location and structure |
As previously discussed on this blog inheritance of genes, the building blocks that determine what we are (e.g. human versus butterfly versus cat), occurs through the inheritance of DNA from both the mother and father. This is why individuals can look like one or both parents, although this is simply due to the types of genes inherited by either parent (through dominant and recessive genes that we inherit). This idea seems simple enough and makes sense when you think about how babies are created, but there is actually a small wrinkle as there is a type of DNA that is inherited exclusively from one parent: mitochondrial DNA (mtDNA). Today's blog post will address what mtDNA is, how it is different from nuclear DNA (which is inherited from both parents), and how it can affect us in both positive or negative ways.
mtDNA (Figure 1) is so named because it is located in the mitochondria of the cell. You may have heard of the mitochondria being the powerhouse of the cell, and this is because it creates the energy used by the cell for cellular functions. There are hundreds and thousands of mitochondria in each cell, leading to millions in the entire body. This organelle of the cell is also unique because it contains DNA separate from nuclear DNA, which is how and why mtDNA received its name.
mtDNA is present as it does serve a specific purpose: it codes for various proteins and ribosomal and transfer RNA. It also controls the function of the mitochondria. It works in conjunction with nuclear DNA for these purposes, so it cannot stand alone and control the major functions of the body (meaning it does not control your eye color or hair texture). mtDNA is also unique in that it is circular versus linear as is the case with nuclear DNA. Additionally, there is a large amount of evidence that demonstrates that mtDNA is exclusively inherited through the mother's line. There has been some new evidence that has challenged this assertion, but the evidence is small and the researchers have requested additional study into the likelihood of paternal inheritance of this DNA.
mtDNA, while not integral in determining what traits one has, can cause some inherited diseases and age related degradation, such as vision and hearing loss, muscle weakness, and other age related diseases. These can be passed down to any offspring, regardless of sex, but they can only be inherited through the mother's genetic contributions. This means that if your father has one of these mtDNA inherited diseases he cannot pass it down to his offspring.
mtDNA, however, is not exclusively scary and should not be feared. Due to the unique nature of mtDNA being inherited through the mother's line it actually provides a unique way of tracing ancestry. mtDNA has been used to trace familial relationships in the past and the present, particularly in reuniting individuals who were taken from their families. mtDNA has also been used to forward the "Mitochondrial Eve" hypothesis, which was one of the earliest DNA studies to demonstrate that all humans can trace their ancestry back to Africa (which has been further supported by fossil evidence).
Bibliography
Chial, H. & Craig, J. (2008) mtDNA and mitochondrial
diseases. Nature
Education 1(1):217
Shiyu Luo, C. A.-C.-H.-L.-C.-J. (2018). Biparental
Inheritance of Mitochondrial DNA in Humans. PNAS, 13039-13044.
U.S. National Library of Medicine. (2019, December
10). Mitochondrial DNA. Retrieved from Genetics Home Reference:
https://ghr.nlm.nih.gov/mitochondrial-dna#
4 comments:
I really liked this blog. It taught me that mtDNA is so named because it is located in the mitochondria of the cell. You may have heard of the mitochondria being the powerhouse of the cell, and this is because it creates the energy used by the cell for cellular functions. .-Josh w
As a ex Biology Major I loved reading this article. The Mtdna is known for being only inherited by the woman gene. This was a very informative Blog!
-Jasmine Hill
mtDNA is present because it serves a specific function: it codes for various proteins as well as ribosomal and transfer RNA. It also regulates mitochondrial function. It collaborates with nuclear DNA for these purposes, so it cannot control the body's major functions on its own (meaning it does not control your eye color or hair texture). mtDNA is also distinct in that it is circular rather than linear, as is nuclear DNA. Furthermore, there is a large body of evidence indicating that mtDNA is only inherited through the mother's line. There is some new evidence that challenges this assertion, but the evidence is limited, and the researchers have requested more research into the likelihood.
xavier stewart
I did not know you could only inherit something specifically from your mother how interesting! There is something similar in psychology where certain disorders are more likely to be passed down to children if the parents have it for example children are more likely to get diagnosed with bipolar if the father has it. Renn Bullard
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