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Archiver > DNA-NEWBIE > 2009-10 > 1256676798


From: Nelda Percival <>
Subject: Re: [DNA-NEWBIE] New DNA matching tool (beta) at 23andme.com
Date: Tue, 27 Oct 2009 15:53:18 -0500
References: <bfd.66b8577a.3817a3b6@aol.com>
In-Reply-To: <bfd.66b8577a.3817a3b6@aol.com>


Hi,

A person should know when discussing MTDNA that it is and isn't a chromosome. it is not part of the count of 23 pairs of chromosomes. Those are located in the nuculas of the cell while the MTDNA is located outside but in the cell. The primary job of mtdna is the power generator for the cell. All cells have mtdna. mtdna is passed in the egg to the child. The Sperm also carrys mtdna - his mothers... but it is used up by the sperm as he swims to find the egg. It is primarily in the tail and if any remains in the sperm as it enters the egg, the egg's system destroys it. thus a child only inherites the mother's mtdna.



Now chromosomes are strings, but mtdna is a complete circle. think of it as a clock. your HRV1 and HRV2 regions are basically between 11:59 and 12:06, the rest of it is coding zone.



Now, if I remember right there is over 17,000 different markers in just the two HRV regions.



23 and me does not test enough to really be usefull, where as FTDNA (my understanding test them all).



Of the 23 chromosomes in the neculas of the cell, one set is the sex chromosomes a Y and an X for male and a XX for a female, the remander 22 pairs are autosomals. Now the Xs and the autosomals combine with each other, and recombine at each generation. this is not a set pattern but randomly.. thus giving you segments of genes from different ancestors. 23and me compares these segments and sets a size limitation.



you can match a very distant cousin, but not match a 2nd cousin. due to the random recombination.



you could or could not even match a sibling, but testing a sibling gives you more information as to what gene segments have been passed down, testing both parents can also let you know what segments came from what parent.



What is a cousin who shares a common ancestor at 11 generations? A third cousins shares a great great grandparent... this test 23andme does allows a person to find by segment matching these lost relationships



nelda




My websites : http://freepages.folklore.rootsweb.com/~bonsteinandgilpin/



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