The Surprising Variability of Mitochondrial DNA
09/03/10 11:41 Filed in: GenomeWeb Daily Scan
Submitted by S. Pelech - Kinexus on Tue, 03/09/2010 - 14:44.
The concept that mitochondrial DNA may vary slightly in nucleotide sequence is hardly that surprising at all. Mitochondria DNA is maternally derived, originally from the oocyte. The oocyte is one of the largest cells in the human body. The average liver cell is known to feature about 1700 mitochondria on average, so an oocyte probably features several times this number. While half of the DNA and centrioles in a fertilized egg are derived from the male, all of the mitochondria and its DNA is from the female. During the reductive cell divisions following fertilization, the populations of mitochondria become portioned out in the daughter cells, which ultimately give rise to different organs following differentiation. It is reasonable to suppose that mitochondria undergo faster rates of replication than the cells that harbor them, so there would be more opportunity for SNP's within mitochondrial DNA to accumulate and be propagated, even within the same individual. Mitochondrial genes may represent the ultimate "selfish" genes from the Richard Dawkin's perspective.
Link to the original blog post
The concept that mitochondrial DNA may vary slightly in nucleotide sequence is hardly that surprising at all. Mitochondria DNA is maternally derived, originally from the oocyte. The oocyte is one of the largest cells in the human body. The average liver cell is known to feature about 1700 mitochondria on average, so an oocyte probably features several times this number. While half of the DNA and centrioles in a fertilized egg are derived from the male, all of the mitochondria and its DNA is from the female. During the reductive cell divisions following fertilization, the populations of mitochondria become portioned out in the daughter cells, which ultimately give rise to different organs following differentiation. It is reasonable to suppose that mitochondria undergo faster rates of replication than the cells that harbor them, so there would be more opportunity for SNP's within mitochondrial DNA to accumulate and be propagated, even within the same individual. Mitochondrial genes may represent the ultimate "selfish" genes from the Richard Dawkin's perspective.
Link to the original blog post