Maternal Ancestry
Overview
Most of the DNA in cells are a combination of both parents’ genetic makeup; however, mitochondrial DNA (mtDNA) is just inherited from the mother. By investigating mutations to the patterns in the mtDNA, individuals can trace their ancestry back to certain groups of humans at different geographic locations. These mutations can often be as small as one base, and are called Single Nuclotide Polymorphisms, or SNPs. This provides an excellent context for students to ask meaningful questions about their own origins and to employ biosensors, a low cost colorimetric assay, to find the answer.
The maternal ancestry experiment has been developed and tested by undergraduate students at Tufts, with support from graduate student and post doc mentors and chemistry department staff. We have also tested the project in high school classrooms. The protocols, worksheets and additional resources are listed below.
Classroom Resources
Title |
Description |
Document |
Maternal Ancestry Overview |
Introduction to how mitochondrial DNA is linked to ancestry. |
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Maternal Ancestry Overview Power Point |
A power point presentation that describes the different steps of the reaction. |
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Maternal Ancestry Map |
This map serves as a dichotomous key showing how different SNPs are associated with haplogroups. |
*to print, choose landscape orientation. |
Prep 1 - Functionalizing Beads |
In this preparatory step, microspheres or beads are "tailed" with a long string of adenines. Due to time, this should be done before class. |
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Prep 2 - Making biosensors |
In this preparatory step, various forms of absorbent cellulose are assembled to make biosensors. Students can easily do this step. |
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Part 1 - mtDNA Collection and Purification and Part 2 - PCR prep |
Students collect their mitchondrial DNA (mtDNA) and purify their DNA using ethanol precipitation, then add the nucleotides, buffers and enzymes needed for PCR. |
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Part 1 - alternate mtDNA Collection |
Students collect their mitchondrial DNA using DNA Genotek collection kits. Teachers can obtain 50 kits for free. |
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Part 2 - alternate mtDNA Amplification using PCR |
Students use primers to select specific regions in their mtDNA for amplification, and prepare samples for polymerase chain reaction (PCR). |
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Part 3 - Ligation |
In order to detect single nucleotide changes in DNA, students use a ligation reaction, in which a common probe and a SNP specific probe either join and produce a signal in Part 4, or don't join and don't produce a signal.. |
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Part 4 - Dehybridization and Biosensor Readout |
Students dehybridize their ligated samples, and use a biosensor to determine which SNPs are at which sites on their mtDNA. |
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Kaitlin Minnehan and Patrice Wagner work on an assay for determining whether saliva samples contain complementary or noncomplementary DNA sequences.