DNA results and discussions

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The Y-chromosome Test.

This test can only be carried out on males since only they have the Y-chromosome. It can be used to show whether any two males are related.

A sample is taken from a person by rubbing a swab on the inside of the cheek.  The Y-chromosome is separated out from the other chromosomes.  The long chain of DNA is split up into small sections called markers.

It may be useful to imagine these markers as a beaded necklace. For example there may be a repeat unit in the small marker chain made up of 3 of the above chemicals e.g. CTG.  This unit may be thought of as a bead in a necklace and may look like this:


This small sequence contains 10 repeat units (or beads).

Other marker chains will be made of a different combinations of A, C, T, G to form the beads, and will have different numbers of beads in the marker (often between 8 and 35 beads per marker).


Each time a cell divides to produce new cells, the DNA chain within the original cell is copied to form a new chain and hence a second cell.  Sometimes the copying goes wrong and leads to genetic mutations.  For example, the above chain may be copied such that there are only 9 CGT ‘beads’ present, not the 10 that were originally present.

Importance of number of Markers tested.

Two tests have been carried out, the first test analysed 10 markers and the second test analysed 25 markers. Generally the more markers that are tested the more conclusive will be the assessment of the likelihood of any two persons being related.



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