The key difference between mitochondrial DNA and chloroplast DNA is that mitochondrial DNA is present inside the mitochondria of eukaryotic cells while chloroplast DNA is present inside the chloroplasts of plant cells.
Mitochondria and chloroplasts are two important membrane-bound organelles in eukaryotic cells. Mitochondria are the powerhouses of cells. On the other hand, chloroplasts are the sites of photosynthesis in plants. Both mitochondria and chloroplasts are believed to be originated from prokaryotic cells to eukaryotic cells through endosymbiosis. These two organelles contain their own DNA. Though this DNA is not a nuclear DNA of a cell and not important for the functioning of the cell, it is important for some of their own cell organelle properties.
CONTENTS
1. Overview and Key Difference
2. What is Mitochondrial DNA
3. What is Chloroplast DNA
4. Similarities Between Mitochondrial DNA and Chloroplast DNA
5. Side by Side Comparison – Mitochondrial DNA vs Chloroplast DNA in Tabular Form
6. Summary
What is Mitochondrial DNA?
Mitochondria are one of the most vital cell organelles present in eukaryotic cells. In fact, they are the powerhouses of eukaryotic cells as they carry out energy production. Mitochondria are double membrane-bound organelles. Electron transport chain occurs in the inner mitochondrial membrane. Mitochondria possess some DNA within the organelle. And, this DNA is important for some of their properties. Moreover, DNA carries different genes important for the proper functioning of the organelles. Mitochondrial DNA is a double-stranded circular DNA present in the mitochondrial matrix. In addition, mtDNA is a synonym for mitochondrial DNA. M. M. K. Nass and S. Nass discovered mtDNA via electron microscopy.
Figure 01: Mitochondrial DNA
Mitochondrial DNA comes from mother to offspring. Hence, it is uniparentally inherited DNA. Unlike nuclear DNA, which is diploid, mtDNA is in ploidy state. A single cell contains several mitochondria. Each mitochondrion contains DNA. Hence, mtDNA is in heteroplasmy state. In comparison to nuclear DNA, mtDNA is small. Human mtDNA constitutes of 16,569 base pairs and possesses 37 genes coding for tRNA, rRNA, and polypeptides. Unlike multicellular organisms, unicellular organisms have linearly organized mtDNA.
What is Chloroplast DNA?
Chloroplasts are the organelles that carry out photosynthesis in plants. These organelles contain photosynthetic pigments called chlorophylls. Similar to mitochondria, chloroplasts also contain their own DNA (plastid DNA). This chloroplast DNA is present in the chloroplast stroma. cpDNA and plastome are synonyms for chloroplast DNA. cpDNA is double-stranded circular DNA.
Figure 02: Chloroplast DNA
Though cpDNA occurs as a single chromosome, it exists as multiple copies. Generally, cp DNA consists of 120,000 to 170,000 base pairs containing about 200 genes. Inside the chloroplast, all CpDNA molecules are combined and exist as a large ring.
What are the Similarities Between Mitochondrial DNA and Chloroplast DNA?
- Mitochondrial DNA and chloroplast DNA are single, circular chromosomes.
- Both DNA types are double-stranded.
- Also, both exist as multiple copies.
- moreover, both are randomly distributed to daughter cells, unlike nuclear DNA.
- Furthermore, they are organelle DNA; hence, they are non-nuclear DNA.
- They are devoid of histone proteins and are not enclosed with a membrane.
- Additionally, both mtDNA and cpDNA do not have introns.
- They are rich in AT regions.
- Besides, both mitochondrial and chloroplast DNA contain genes that are important for their functioning.
- In comparison to nuclear DNA, both mtDNA and cpDNA are small in size.
What is the Difference Between Mitochondrial DNA and Chloroplast DNA?
Mitochondrial DNA is present inside the mitochondria while chloroplast DNA is present in chloroplasts. So, we can consider this as the key difference between mitochondrial DNA and chloroplast DNA. Furthermore, human mitochondrial DNA contains 16,569 base pairs while chloroplast DNA contains 120,000 to 170,000 base pairs. Thus, this is also a significant difference between mitochondrial DNA and chloroplast DNA. Additionally, the mitochondrial genome contains 37 genes while chloroplast genome contains about 200 genes.
Below infographic summarizes the difference between mitochondrial DNA and chloroplast DNA.
Summary – Mitochondrial DNA vs Chloroplast DNA
Both mitochondria and chloroplasts have their own DNA as mitochondrial DNA and chloroplast DNA. Moreover, both types of DNA are double-stranded circular DNA which occurs in multiple copies. Compared to mitochondrial DNA, chloroplast DNA is large in size and contains more genes. Thus, this is the summary of the difference between mitochondrial DNA and chloroplast DNA.
Reference:
1. “Mitochondrial and Chloroplast DNA.” LinkedIn SlideShare, 19 Oct. 2017, Available here.
2. “Chloroplast DNA.” Wikipedia, Wikimedia Foundation, 24 Feb. 2019, Available here.
Image Courtesy:
1. “Mitochondrial DNA lg” By National Human Genome Research Institute – National Institutes of Health. National Human Genome Research Institute. “Talking Glossary of Genetic Terms.” Retrieved November 17, 2016, (Public Domain) via Commons Wikimedia
2. “CtDNA” By Kelvinsong – Own work (CC BY-SA 3.0) via Commons Wikimedia