Tag Archives: genetics

Strawberry DNA

Here’s a neat article I found in my Feedly posts today. Click “Imagination Station” for a simple explanation of the DNA extraction process. They’re using strawberries in the video, but, as you’ll see, you could try it on just about any living matter…including yourself.

The problem, of course, is other than having a dish of cloudy material as in the video, actually seeing the DNA you extract is a completely different story!

Have you done any DNA testing? Three major companies are in the DNA business: FamilyTreeDNA,  23andMe and AncestryDNA. Which test you take will be driven by the purpose of taking the test in the first place.  The short story is this: The most popular test today is the Autosomal DNA test or atDNA test. All three companies do this test. Keep in mind that there are 23 chromosomes in every nucleus of every cell in your body. One of those chromosomes is the sex chromosome which is either X-X or X-Y. This chromosome determines whether your are female (X-X) or males (X-Y).DNA_animationThat leaves 22 that are made up of a recombination of the DNA from your father (roughly 50%) and your mother (roughly 50%). It’s the recombination process that determines which of your father’s traits you will inherit and which of your mother’s. That’s also why siblings can either vary a great deal in their appearance or, if their appearances seem quite similar, one may have red hair and the other brown.

Logically, if you’ve got 50% of your mother’s atDNA and she received 50% from each of her parents, you can only have 25% from each of her parents. The same holds true with your father’s atDNA and that what makes up the 50% you inherited from him, 25% of which is from his father and 25% from his mother. The farther back you go up your family tree while applying the fact that the 50% gets halved at each generation. You’ll have 12.5% from each of your 8 great-grandparents, 6.75% from each of your 16 2nd great-grandparents.  Then take into account the billions of possible ways that each recombination can produce, it gets a little tricky to go very far beyond 5 or 6 generations. We refer to it as a “cousin finder.” Ethnicity can be inferred to some degree and in broad generalities: Northern European, Sub-Saharan African,  Ashkenazi Jew and so forth.

The second and third types of tests will take you deep into the genetic histories of your direct maternal or paternal lines. Only men have and thus can pass along Y-DNA. A man gets his from his father who got his from his father and so on. So to trace a paternal line, the Y test is quite useful for 2 reasons. It’s biologically impossible to get a Y chromosome from a male ancestor other than from your direct line. And it mutates at a very slow rate meaning that it stays relatively intact for thousands of years, unlike atDNA which “melts” in each generation.

The third test is for mitochondrial DNA, the mother’s unique contribution to the equation. Unlike the Y, mitochondrial or mtDNA is in everyone’s cells. For the lack of a more scientific answer, it is what powers the cells, allowing them to live, divide and recombine so that life can go on.  But, only the mother passes the mtDNA even though both she and the father have it.

Here’s the reason. Mom has her Mom’s mtDNA and Dad has his Mom’s mtDNA. At the point of conception, the ovum contains mom’s mtDNA as she supplied the ovum containing it. Dad supplied the sperm but the mtDNA is in the tail. Picture your science books where the sperm wiggles its way to its destination. At the moment of conception, the tail falls off and thus the mtDNA from the father is no longer a factor. It’s a lot like a space rocket. Once the rocket clears earth’s atmosphere, the boosters fall away. They’ve done their job!

The mtDNA will take you backwards to your mother, her  mother and her mother’s mother and so on.

Both Y and mtDNA can give you reasonably accurate description of your genetic background. But it is important to say that as far as family research is concerned, DNA tests do not replace standard research practices. It will only help to prove or disprove what you’ve discovered.

For a more detailed explanation of DNA and the various types and tests, there are some excellent bloggers whose backgrounds in the science is much deeper than my own:

That should be more than enough to get you started! Good luck!

Visit Old Bones Genealogy of New England at www.oldbones.info

Lots happening

Last night was Session 2 of a 4 part class I’m holding at the Wilbraham Public Library on the basics of genealogy and family research. The first session went very well and everyone in attendance seemed to get a lot out of it. Well, I guess it was a good session because last night, about twice as many people as the first session showed up!! A wide variety of participants in the group: Some have done a substantial amount of research but most have only dabbled or are just beginning. We spent most of the night discussing web sites and went to a few so I could show them some shortcuts to their research. Lots of great interaction and we actually went over by about 45 minutes in the Q&A!!

Next, I finally registered to attend NERGC, the New England Regional Genealogy Conference. Karen and I went to the last conference which was held down the road in Springfield. Next year’s conference will be in Manchester, NH. I really got a lot out of the last one and I’m looking forward to this one. Many speakers, many subjects covered and much to learn. The easy part is registering; the hard part is trying to pick the sessions to attend. There are probably 5 or 6 different subjects being covered in each time frame such as DNA/genetics, the National Archives, immigration and naturalization, writing and publishing your work, advanced on-line research techniques and many more. I’ll also be leading one of the discussion groups at a luncheon on Saturday sponsored by the New England Chapter of the Association of Professional Genealogists.

And at last, I was able to register for the on-line “Certificate in Genealogical Research” course at Boston University. It begins January 16, 2013 and runs for 15 weeks. When that’s complete, I’ll begin the official certification process through the Board for Certification of Genealogists (BCG). As I get deeper and deeper involved in specific areas of research, I discover that I don’t know what I don’t know! Basically, it ain’t easy!