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Posts Tagged ‘mutation’

One thing that DNA testing for genealogy shows is,  if you are a male, you have the same biological component as your father, your grandfather, your great-grandfather, your great, great grandfather and your g-g-g-g-g-grandfather.

That component is called the Y-chromosome, part of the genetic ribbon of information that makes every male, male.   When you test your Y-DNA, you can determine whether you are or are not related to another male with the same surname.  You might even want to join the growing list of surname projects going on across the country.

DNA, or deoxyribonucleic acid, exists in almost all cells and is the building block for a human being.  DNA determines genetics and whether your eyes are blue and your hair is straight.  It also predicts the risk for health disorders or diseases, so there is much to be learned through DNA testing that goes beyond ancestry.

The way genealogists approach DNA testing is they look for mutations.  In other words, a mutation is a change in the DNA sequencing.  Cells in our body increase by dividing in a process called mitosis.  An enzyme called polymerase uses the original DNA helix as a template and then builds a whole new cell using the same DNA code.

Occasionally a mutation in this process occurs and gets passed on.  It is rare; approximately 0.2% per generation, but it does signal a break in the identical ancestral code that gets passed from father to son.

There are DNA genealogy tests for women, even if they do not have a Y chromosome.  For women, scientists rely on the mitochondrial DNA which gets passed from the mother to all her offspring.

It’s fascinating that with the help of a single cheek swab DNA testing for genealogy can track the history of your surname, or even your ancient ancestors as they migrated from East Africa 80 thousand years ago.

To understand genealogical data, we must first learn about the role of DNA.  It is the primary molecule of life and is responsible for the development and growth of every living thing.

The best way to describe the amount of genetic information stored in DNA is to picture a library full of books.  If you took every line of copy in every page of every book and you cut it into strips and taped them one after another, end to end, you would have the equivalent information that DNA stores in our bodies.

With DNA all this information is organized into shelving called chromosomes.  In the library you seek information by alphabet then shelf number then page and finally paragraph.  The Human Genome Project did essentially the same thing in 2002, by creating a “card catalog” for all the genetic information in the body.

The biggest difference between the way books are cataloged in a library and genetic information is stored in DNA, is there are two copies of the information in each cell; one copy comes from the mother and the other comes from the father.   Both copies are nearly identical which is how paternity is determined.

The biggest difference between males and females lies in the chromosomes.  The 23rd pair consists of an X and a Y.  Females have two “X”s and males have an “X” and a “Y”.  When a baby is conceived the mother always passes down an X, but the father can pass down either an X or a Y; X for a baby girl and Y for a baby boy.

To trace ancient ancestral roots, genealogists look at the DNA with low rates of change or mutation, making genealogical data a reliable but imperfect source of information from up to 150,000 years ago.