NextGen Genealogy: The DNA Connection by David R. Dowell

The info-book divides into eight chapters preceded by a four-page preface with acknowledgments and notes and succeeded by 14 pages of bibliography, glossary, and index.

The 16-page first chapter explains deoxyribonucleic acid as:

• mitochondrial DNA (mtDNA) in the food-energizing mitochondria surrounded by the cytoplasm between the cell membrane and the cell nucleus;
• nuclear DNA in 22 pairs of autosomes and one pair of gender-differentiating sex chromosomes in the cell nucleus.

It furnishes questions to answer regarding genealogical research untangling adoption, brick-wall roadblocks, ethnicity or surname origins in order to match genetic test type with genetic testing motivations of:

• curiosity;
• data preservation in more durable forms than human memory;
• family history research;
• health history and personalized genome medicine. 

The 26-page second chapter goes over Y-chromosome testing of male DNA (yDNA) which disproves relationships more conclusively than it establishes definitive lines of descent and which fathers transmit only to sons.

The 15-page third chapter handles mitochondrial DNA that daughters and sons inherit from mothers, survives after all other DNA expires, and traces female lines back into the deep past.

The 33-page fourth chapter identifies autosomal DNA (atDNA) that daughters and sons inherit at the rate of one each from both parents regarding 22 pairs of autosomal chromosomes and which may detect third, fourth, and fifth cousins.

The 11-page fifth chapter juggles X-chromosomes (xDNA) that daughters inherit from both parents and sons from mothers regarding female lines. 

The 22-page sixth chapter knits male and mitochondrial DNA into the extreme genealogies of haplogroups (most ancient common ancestors) known as:

• Y-chromosome Adam 338,000 years ago;
• Mitochondrial Eve 140,000 years ago.

Extreme genealogy leads descendants from eight-generation pedigree chart ideals to expansions from Africa 120,000 to 150,000 and 55,000 to 75,000 years ago to:

• Asia 40,000 to 70,000 years ago;
• Australia 40,000 to 60,000 years ago;
• Europe 35,000 to 50,000 years ago;
• Americas 15,000 to 35,000 and 8,000 to 10,000 years ago.

The 25-page seventh chapter mentions genetic testing as ethnically balancing or imbalancing technology and values.

The five-page eighth chapter notes in conclusion optimal results from testing three-plus generations of as many close relatives as possible. 

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Although commonly depicted as an "orange sausage with a blob inside of it" (as shown here), mitochondria may take many shapes.
diagram of simplified structure of a mitochondrion: Kelvinsong; modified by Sowlos, CC BY SA 3.0, via Wikimedia Commons @ https://en.wikipedia.org/wiki/File:Mitochondrion_structure.svg

typical mitochondrial network (green) in two human cells (HeLa cells)
"Fluorescent microscopy picture of HeLa cells expressing a mitochondrially targeted version of green fluorescent protein (mtGFP)"; Monday, Dec. 22, 2014: Simon Troeder (S.Y.M.B.I.O.N.T.), CC BY 4.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:HeLa_mtGFP.tif

Mothers pass mitochondrial DNA to their offspring.
Mitochondrial DNA occurs as a small circular chromosome within mitochondria.
credited to Darryl Leja, NHGRI (National Human Genome Research Institute); Thursday, Aug. 28, 2014, 14:52:00: National Human Genome Research Institute (NHGRI Image Gallery), CC BY 2.0, via Flickr @ https://www.flickr.com/photos/genomegov/27249944414/

Nuclear versus mitochondrial DNA:
Unlike nuclear DNA (left), mitochondrial DNA is only inherited from the maternal lineage (right).
University of California Museum of Paleontology (UCMP) and the National Center for Science Education: CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Mitochondrial_DNA_versus_Nuclear_DNA.gif

Single nucleotide polymorphisms (SNPs; "snips") may act as biological markers, predict ancestry or ethnicity or even inspire genetic symphonies. TED 2012 attendees were treated to genetic symphonies based upon specific genetic markers in their DNA samples.
American businessman and venture capitalist Steve Jurvetson's genetic symphony reflected four SNPs (KIBRA short term memory; ACTN3 sprinter gene; ADRA2A sweet tooth; AHR caffeine consumption).
Long Beach Performing Arts Center, Long Beach, Los Angeles County, Southern California; Thursday, March 1, 2012, 12:17:18: Steve Jurvetson (jurvetson), CC BY 2.0, via Flickr @ https://www.flickr.com/photos/jurvetson/6949675537/

Dowell, David R. 2014. NextGen Genealogy: The DNA Connection. Santa Barbara, CA, USA; Denver, CO, USA; Oxford, England, UK: Libraries Unlimited.