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ISOGG's Online Course |
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Lesson 1.1 Introduction to DNA testing and technical terms Everyone has a least one ancestral line where the paper trail ends. This fact leads many genealogists to try the latest tool available to surpass their paper trail brick-walls: genetic genealogy. Known widely as genealogical DNA testing, it became commercially available to genealogists in the year 2000. To understand how DNA testing can be applied to genealogy, you may need a refresher on gender chromosomes from your high school biology days. Remember the female chromosome is called the "X" chromosome and the male chromosome is called the "Y"? If you're a female, you have received one X from your mother and one X from your father. If you're a male, you received an X from your mother and a Y from your father. Y-Chromosome DNA Testing Scientists discovered an area on the Y-chromosome
that does not mix (the technical term for this is "recombine"). This area on the
Y-chromosome changes (or "mutates") very slowly over time.
Since the Y-chromosome is passed from father to son on down a male line,
as are surnames in some societies, it was realized that Y-chromosome DNA
testing could be used to determine whether two males with the same surname shared a common ancestor. Review 1. Only males have the Y-chromosome. 2. Most of the Y-chromosome DNA does not mix, or recombine. 3. The Y-chromosome changes very slowly, or mutates over time. 4. The Y-chromosome is passed down the male line from father to son in the same way surnames are in many societies. Definitions Mutates - A permanent
structural alteration in DNA. In
most cases, DNA changes either have no effect or cause harm, but
occasionally a mutation can improve an organism's chance of surviving and
passing the beneficial change on to its descendants.2
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