Mitochondrial DNA Notes 13.3

DNA Nuclear DNA Mitochondrial DNA (mtDNA) 23 pairs of chromosomes in the nucleus in which each parent contributes the chromosomes Mitochondrial DNA (mtDNA) Located outside the nucleus and contains DNA only from the mother

Mitochondria Organelles that break down glucose in the presence of oxygen in a process called cellular respiration

Advantages A single mitochondrion contains several loops of DNA Hundreds of mitochondria in each cell Can be used when nuclear DNA is degraded (fire) or only a small amount is present (hair shaft) A reference sample can be obtained from any maternally related relative More sensitive than nuclear DNA Plays a key role in the ID of human remains

Disadvantages More time consuming, costly, and rigorous Only used by a few public and private labs FBI has imposed strict limitations on the cases for which mtDNA technology can be used

How is mtDNA different from nuclear DNA mtDNA is circular or a loop each loop contains approximately 37 genes Two regions are highly variable in humans Region I (HV1) and region II (HV2) Base sequences from HV1 and HV2 are available by the FBI lab and the Armed Forces DNA Identification Lab

How is mtDNA different from nuclear DNA cont. mtDNA contains 5,000 sequences Permits an assessment of how common or rare an observed sequence is

Important Note mtDNA does not approach STR in its discrimination power and is best reserved for samples for which nuclear DNA is not possible to attain

In-Class Assignment/Homework Ch. 13 Critical Thinking