Mitochondrial DNA

What are mitochondria?

Organelles that produce energy

Who is mitochondria inherited from?

Only the mother

Does mitochondrial DNA mutate faster than nuclear DNA?

Yes as it lacks repair enzymes

What happens to mitochondrial DNA after death?

DNA slowly degrades

Can you amplify mtDNA form preserved tissues and skeletons?

Yes, you can often amplify mtDNA but nuclear DNA from preserved tissues and skeletons

What type of genome does mitochondrial DNA have?

Circular genome, with no non-coding DNA

Can mitochondrial DNA survive in fossils?

Yes

What are the differences between nuclear and mitochondrial DNA?

What does mtDNA analysis involve?

• Hypervariable segment (D-loop)

• Restriction digestion → DNA cut → RFLPs → Haplogroups (shared with specific ethnicities)

• Sequencing of control region (HVR1 & HVR2) → Haplotype (individual family type)

• Sequence DNA → pair-wise comparisons

When was the use of mtDNA pioneered?

In the 1980s, Allan Wilson pioneered the use of mtDNA to study human evolution. mtDNA sequences of indigenous people worldwide were compared to determine the common ancestral mtDNA sequence

What was found regarding mtDNA and human evolution in the 1980s?

• The root of the tree is in Africa and is 200,000 years old

• Calibration of the molecular clock with chimp out-groups indicate the common ancestral sequence existed 100,000 to 300,000 years ago

• African populations are more diverse than non-African

• Non-African mtDNAs are closely related

What is coalescent theory?

A method to trace genetic lineages backward in time to their common ancestor

Who is Mitochondrial Eve?

The most recent common ancestor of all humans through the maternal line, identified using mtDNA and coalescent theory