Difference Between Y DNA and mtDNA

The main difference between Y DNA and mtDNA is that the Y DNA is inherited from the father whereas the mtDNA is inherited from the mother. Furthermore, Y-DNA occurs inside the nucleus while mtDNA occurs inside the mitochondria. Also, Y-DNA is a part of the genomic DNA but not the mtDNA.

Y-DNA and mtDNA are two types of hereditary materials that can occur inside nearly all types of cells in the body. Importantly, Y-DNA undergoes mutations while passing over the generations, but mtDNA remains unchanged.

Key Areas Covered

1. What is Y DNA
     – Definition, Structure, Significance
2. What is mtDNA
     – Definition, Structure, Significance
3. What are the Similarities Between Y DNA and mtDNA
     – Outline of Common Features
4. What is the Difference Between Y DNA and mtDNA
     – Comparison of Key Differences

Key Terms

Genomic DNA, Hereditary Material, Inheritance, mtDNA, Mutation, Y DNA

What is Y DNA

Y-DNA is the DNA in the Y chromosome of males. It exclusively passes down from father to son. And, this Y chromosome serves as the sex-determining chromosome of many species since the other sex chromosome, which is the X chromosome, occurs in both males and females. In the human genome, the Y chromosome is the smallest chromosome, and its size is around 60 million base pairs. Also, the Y chromosome has the least number of genes among human chromosomes. Furthermore, the genes in the Y chromosome are expressed hemizygously since only one Y chromosome occurs per genome under normal conditions. The SYR gene is responsible for the development of testis.

Figure 1: Human Y Chromosome Structure

Moreover, recombination between Y chromosome and X chromosome is harmful since it can produce Y chromosomes without necessary genes. However, only the tips of these chromosomes can recombine. For instance, multiple cell divisions that occur during the production of a sperm can cause a high mutation rate. Moreover, the Y chromosome is considered as a genetic wasteland since it is on a trajectory to completely disappear from the human genome. Its rate of losing genes is 4.6 genes per million years. Over the course of existence, it has lost 1,393 of its 1,438 original genes.

What is mtDNA

mtDNA is the mitochondrial DNA that occurs exclusively inside the mitochondria. Therefore, mtDNA is not a part of genomic DNA. Generally, mtDNA is a circular molecule, which is covalently-closed. Also, the size of the mtDNA is very short when compared to the chromosomes in the genomic DNA. Only 37 genes are encoded in it. In most species, mtDNA is inherited from the mother since paternal mitochondria die shortly after fertilization. Furthermore, mutations in the mtDNA are rare, and they occur per 20,000 years.

Figure 2: Human mtDNA Structure

Mitochondrial mutations are the significant contributors to the ageing process and age-associated pathologies. Moreover, they can contribute to a number of disorders including exercise intolerance and Kearns–Sayre syndrome.

Similarities Between Y DNA and mtDNA

• Y-DNA and mtDNA are two types of hereditary materials inside the eukaryotic cell.
• Both types of DNA occurs inside compartments but, not in the cytoplasm.
• Also, both are inherited from the parents.
• Furthermore, genealogical tests can determine the ancestral relationships between individuals based on these types of DNA.
• Besides, both are the most suitable haplogroups for the study of human genetics. A haplogroup is a group of traits inherited from a single parent.

Difference Between Y DNA and mtDNA

Definition

Y-DNA refers to one of the two types of sex chromosomal DNA transmitted from father to son while mtDNA refers to the small circular chromosome found inside mitochondria. Thus, this is the main difference between Y DNA and mtDNA.

Size

The size of the Y-DNA is 59 million base pairs while the size of the mtDNA is 16,569 base pairs. Hence, this accounts for another difference between Y DNA and mtDNA.

Number of Genes

The number of genes in them is also a difference between Y DNA and mtDNA. Y-DNA consists of over 200 genes including 72 protein-coding genes while mtDNA only consists of 37 genes. 

Structure

Also, Y-DNA occurs in an acentric and linear chromosome, containing a short p-arm and a significantly long q-arm while mtDNA is a circular, covalently closed, double-stranded DNA.

Location

Another important difference between Y DNA and mtDNA is that Y-DNA occurs inside the nucleus while mtDNA occurs inside the mitochondria. 

Genomic DNA

Moreover, Y-DNA is a component of genomic DNA while mtDNA is not a component of genomic DNA.

Sex Difference

Y-DNA only occurs in males while mtDNA occurs in both males and females. Hence, this is another difference between Y DNA and mtDNA.

Animals and Plants

Besides, Y-DNA only occurs in mammals while mtDNA occurs in both animals and plants.

Transcription

Furthermore, Y-DNA produces monocistronic mRNAs while mtDNA produces a single polycistronic mRNA.

Inheritance

Aboveall, one main difference between Y DNA and mtDNA is that the Y-DNA passes along the patrilineal line while the mtDNA passes along the matrilineal line.

Mutations

Importantly, Y-DNA undergoes mutations while mtDNA does not undergo mutations.

Evolution

Another difference between Y DNA and mtDNA is in the evolution process. Y-DNA is the fastest-evolving part of the human genome while mtDNA serves as a tool for the evaluation of relatedness of populations due to its conserved sequence over generations.

Ancestor

We can trace back all Y-DNA to a single prehistoric father, “Y chromosomal Adam” while we can trace back the mtDNA to one woman, “Mitochondrial Eve”. They lived about 100,000-200,000 years ago.

Conclusion

Y-DNA is the Y chromosomal DNA inherited from father to son. On the other hand, mtDNA is inherited from the mother to both son and daughter. Y-DNA is large and contains more genes than mtDNA. Also, Y-DNA occurs inside the nucleus while mtDNA occurs inside the mitochondria. In addition, Y-DNA undergoes mutations rapidly while mtDNA remains unchanged. Thus, the main difference between Y DNA and mtDNA is their structure, inheritance, and evolution.

Reference:

1. Maan, Akhlaq A et al. “The Y chromosome: a blueprint for men’s health?” European journal of human genetics : EJHG vol. 25,11 (2017): 1181-1188. Available Here
2. Chinnery, Patrick Francis and Gavin Hudson. “Mitochondrial genetics” British medical bulletin vol. 106,1 (2013): 135-59. Available Here

Image Courtesy:

1. “Human chromosome Y – 400 550 850 bphs” By National Center for Biotechnology Information, U.S. National Library of Medicine (Public Domain) via Commons Wikimedia  
2. “Mitochondrial DNA en” By derivative work: Shanel (talk)Mitochondrial DNA de.svg: translation by Knopfkind; layout by jhc – Mitochondrial DNA de.svg (CC BY-SA 3.0) via Commons Wikimedia