Understanding DNA and DNA Testing

DNA Quiz 1. What is true about DNA? a. It contains the instructions that control the daily workings of your cells. b. It makes up the genes of an organism. c. It’s passed down from parents to offspring.. d. It’s made of deoxyribonucleic acid. e. All of the above 2. Where in your cells is DNA found? a. The nucleus b. The ribosome c. The mitochondria d. a and c e. a and b Most DNA is located in the cell nucleus and called nuclear DNA, but a small amount of DNA can also be found in the mitochondria, mitochondrial DNA.

3. What are genes? a. Units of inheritance passed on from parents to offspring. b. Something you wear on your legs. c. Segments of a chromosome. d. They determine the traits inherited from your parents. e. a, c, and d 4. How many chromosomes do humans have? a. Depends if you are male or female. b. 48 c. 23 pairs d. Different individuals have different numbers of chromosomes.

5. Why is DNA important in family history work? a. It is another record of our family relationships. b. It can provide clues about our ethnicity. c. By using DNA with traditional genealogy it’s possible to go much deeper into our ancestry. d. We can connect and collaborate with our cousins. e. All of the above.

DNA Summary 1. DNA is found in 2 places in the cell. Most DNA is packaged in chromosomes in the nucleus. Mitochondria have a small amount of their own DNA in the shape of a ring. 2. Humans have 23 pairs of chromosomes- 22 pairs are autosomal and 1 pair are the sex chromosomes, X and Y.

DNA Summary 3. The autosomal pairs often exchange segments in a process called recombination. 4. Thousands of genes are found on each chromosome. 5. These genes, all together called the human genome, determine the traits exhibited by the person.

The Four Types of DNA Types of DNA

X Chromosome DNA A mother passes one X chromosome to every son and daughter. 2. A father passes his only X chromosome just to his daughters. 3. X chromosome DNA contains DNA from some but not all of a person’s ancestors. 4. X chromosome analysis is not often used for genealogy.

Y Chromosome DNA 1. One of the 23 pairs of chromosomes present only in males. 2. Follows the unbroken male line (the surname line) from father to son. 3. Y chromosome testing is only informative about a small portion of ancestors. 4. Women interested in having Y testing done to study their paternal line need to have their father, uncle or brother tested. 5. Y testing been used to identify descendants of Scottish and Irish royal lines, Genghis Khan and other famous individuals. Y Chromosome DNA

Mitochondrial DNA This mitochondrial DNA, found in both men and women, is passed through the maternal line and contains information about a smaller number of ancestors, but goes back thousands of years. mDNA/

Inheritance Patterns of Y and Mitochondria Chromosomes Mitochondrial DNA inheritance (the maternal line) is shown in red and the Y DNA inheritance (the paternal line) in blue.

Autosomal DNA 1. Most popular 2. Most affordable 3. Looks at all pedigree lines 4. Can help break through brick walls. 5. Abundance of data Autosomal DNA

Autosomal Genetic Inheritance 50% 50% 50% 50% We pass many things down from generation to generation- surnames, given names, pictures, stories, heirlooms and DNA. 50% 50% 50% 50% Molly

Inheritance of Autosomal DNA Segments of each parents’ DNA, are mixed up, before they are passed on to their children. Individuals don’t inherit the same DNA as their siblings unless they are identical twins. The DNA you inherit determines your own unique genetic makeup, your genome. Autosomal DNA testing provides a good estimate of your ethnic origins- ethnicity.

What information is shown for Ancestry DNA results?

One of the most important aspects of autosomal DNA analysis is identifying common ancestors between individuals as well as common ancestors between multiple matches. Your DNA is compared to everyone else who has taken the test. As new individuals take the test their information is also compared to yours. Matching is determined by how much DNA you share with an individual. The categories are: Parent/Child Immediate family First cousin Second cousin Third cousin Fourth cousin Distant cousin Each DNA circle is based on a shared ancestor. DN circles build a network of individuals who share DNA and have the same person in their tree. While every member of a circle may not share the same DNA segment with every other member of the circle, every member will have a matching segment with at least one member of the circle. Even if they are not connected to you in the circle they are probably a cousin. Ancestry/

Sibling’ Ethnicity Results from Ancestry Autosomal DNA Test Your results for DNA testing can look different than that of your siblings because the DNA you inherited is unique to you. Taken from Ancestry Academy Ancestry.com

Companies Offering DNA Testing Company 23andMe Family Tree DNA (FTDNA)  Ancestry DNA Test Type Autosomal Autosomal, Y and mitochondrial Cost $99 $99- $199 Provides Ethnicity Raw data can be uploaded to other websites. Integrates with My Heritage family tree. Health testing High privacy Best for Y and mitochondrial test. Cousin matches Raw data can be uploaded to other websites. Links DNA results to your Ancestry family tree. Sample Saliva Cheek swab Number of people in the data base 1,000,000 About 150,000 Since 23andMe does health testing, they have to build extremely high privacy walls around their customers.

Getting a match through autosomal DNA testing is most valuable when you can open a line of communication with your newfound cousins. Then you can share genealogical data like surnames, geographic origins and pedigrees.