Genealogical DNA Testing
Ongoing developments in DNA testing procedures have provided new ways for people to trace their genealogical backgrounds. Current testing techniques can also serve as a form of evidence in criminal cases when a suspect's identity is in question. DNA materials hold information regarding possible relatives who are living as well those in a person's ancestral lines.
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DNA
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DNA molecules---also known as deoxyribonucleic acid---contain 23 pairs of chromosomes that act as the coding blueprint for most living organisms, according to the Reinyday Guide to Genealogical DNA Testing. Four nucleotides make up the building blocks for DNA: T (thymine), G (guanine), A (adenine) and C (cytosine). The particular sequence in which nucleotides appear determines what traits a person or organism will have. DNA testing can provide information on a person's genealogy based on how the nucleotides are sequenced within his DNA material.
Maternal Ancestry
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A person's maternal ancestral line is one of the areas explored through genealogical DNA testing methods. This information is obtained from the mitochondrial DNA materials (mtDNA) that reside outside of a cell's nucleus, according to the Reinyday Guide to Genealogical DNA Testing. Genetic material contained inside the mitochondria exists outside of the 23 chromosome pairs contained in the nucleus. And though men and women both carry mtDNA material, genealogical information is only passed down through mother-daughter generational lines.
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Paternal Ancestry
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A person's paternal ancestral line is another area explored through genealogical DNA testing methods. This information is contained within the Y-chromosome (Y-DNA) material, which is only present in males, according to the Reinyday Guide to Genealogical DNA Testing. Testing methods that use the Y-chromosome can trace paternal ancestry through multiple generations. Y-chromosome materials reside in the cell nucleus and remain relatively unchanged from generation to generation, while other nucleus genes can undergo alterations across generational lines.
Y-Chromosome Testing
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As males possess the XY chromosome make-up, certain areas of the Y-chromosome remain intact while other areas intermix with the X-chromosome, according to the Reinyday Guide to Genealogical DNA Testing. Areas where X and Y join contain repeating DNA segments, also known as short tandem repeats. Repeating segments can indicate certain traits or characteristics in a family line or may be specific to that individual. Genealogical DNA testing examines each segment and assigns a number to each one.
mtDNA Testing
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The DNA testing procedures done with mtDNA are based on the mitochondria organelles contained inside cells, according to the Reinyday Guide to Genealogical DNA Testing. Mitochondria contain the rDNA portions of the genetic code, which play a pivotal role in carrying out a cell's genetic instructions. Testing results are based on the Cambridge Reference Sequence, which acts as a comparison model when determining a person's mtDNA genealogy. Nucleotide code sequences are segmented, much like with Y-chromosome testing. Alterations in code sequences can indicate mutations specific to a particular family line.
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