Mitochondrial DNA

Mitochondria, the oxygen-processing factories of eukaryotic cells, have their own DNA, a relic from the distant past when they were free-living organisms.

Organism Code Amino Acid (standard)
All nonplant species UGA Tryptophan (stop)
Mollusks AGA Serine (Arginine)
Yeast CUU Threonine (Leucine)

(For those who may be interested, here is the entire sequence of a human mitochondrial DNA.)

Another significant difference in mitochondrial DNA is that it is circular, like the DNA of prokaryotes.

Mitochondrial DNA is inherited ONLY in the maternal line; all of the mitochondrial DNA in any living human came from that individual's mother.

Bryan Sykes, at the Institute of Molecular Medicine in Oxford, has summarized the work of his group and several others:

Sykes gave these women names, and in a book called "Seven Daughters of Eve", explained the methodology and presented imaginary lives for the women.

Notice in the graphic that the lines converge in the upper center. Now apply this logic:

Sykes calls this woman Mitochondrial Eve, and estimates that she lived about 130,000 years ago, in East Africa.

Another interesting case: Otzi, the Tyrolean iceman.

Similar analyses can be applied to the Y chromosome:

Cavalli-Sforza and collaborators [Science, 2008, 319, 1100] have taken the tracing of our ancestry in a more general direction.

The data are consistent with a single origin for humanity in sub-Saharan Africa, with homo sapiens spreading around the world during the past approximately 100,000 years.

The message from our DNA is clear: we are all brothers and sisters.

[A good review of both the genetic and paleontological data on the human migration: Lalueza-Fox and Gilbert, Curr. Biol., 2011, 21, R1002.]


This page last modified 1:19 PM on Tuesday January 28th, 2014.
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