Mitochondrial DNA
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Mitochondria arose from commensal intracellular bacteria in
eukaryotic cells
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Contain own genome (circular molecule) and own ribosomes
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In sexual reproduction, only the egg cell contributes mitochondria to
zygote
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Thus, inheritance follows maternal line only, no recombination with
other mitochondrial genomes
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New alleles arise by mutation only
Map of human
mtDNA genome
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Investigative uses of mtDNA
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Small molecule, easier to recover from very old materials, in
comparison with nuclear DNA
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D-loop (control) region highly variable since it contains no
transcribed genes; use variation in this region to track recent
evolutionary events
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Origin of Pacific island populations? East from Asia or west from the
Americas?
Easter Island (Rapanui)
Cook Islands, etc
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Origin of Native Americans?
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References: Sykes, “The Seven Daughters of Eve”; Wells, “The
Journey of Man”
Analysis of mtDNA sequences
Dolan DNA Learning Center – information about mtDNA experiment:
http://www.geneticorigins.org/geneticorigins/
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Haplotype: combination of alleles at multiple loci that are (typically)
transmitted together on the same chromosome
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Haplogroup: group of similar haplotypes related by ancestry
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Analysis of many mtDNA sequences from various ethnic groups has
resulted in the development of haplogroup trees and inferred maps of
human population migrations
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Recovering the Romanovs
1917 – Tsar Nicholas II abdicates the throne of Russia, family is
imprisoned
1918 –Russian royal family executed in Yekaterinburg, Siberia
1991 – After dissolution of USSR, remains recovered from area;
analysis revealed 9 sets of skeletal remains, whereas 11 had been
expected (family members and servants)
1994 – Testing of mtDNA from remains by comparison with living
maternal-line relatives confirms that 5 sets of remains are Romanov
family members: Nicholas, Alexandra, and 3 daughters; the other four
sets are unrelated (servants)
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Recovering the Romanovs
1998 – The 5 sets Romanov remains are buried in the Cathedral of
Saints Peter and Paul in St. Petersburg, Russia
2007 – 2 additional sets of remains are recovered from a site near to
the original recovery site; skeletal analysis reveals that these are of the
correct age to be the missing son and daughter of Nicholas and
Alexandra
2008 – DNA testing confirms that these are the remains of the missing
children
Link to Dolan DNA Learning Center curriculum materials on
“Recovering the Romanovs”: http://www.dnai.org/d/index.html
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