Glossary
| Allele | Mitochondrial DNA (mtDNA) |
| Allele Frequency | Mutation |
| Autosomal DNA | Mutation Rate |
| Chromosome | PCR |
| DNA | Primer |
| Junk DNA | Sex Chromosomes |
| Locus | SNP |
| Nucleotide bases | STR |
Allele - One of two or more forms that can exist at a single gene locus. For example, on the Y chromosome, individual #1 may have 12 repeats and individual #2 may have 14 repeats. This represents a difference or mismatch at that locus.
Allele Frequency - A measure of the commonness of an allele in a population.
Autosomal DNA - Any chromosome that is not a sex chromosome. There are 22 pairs of autosomes in the normal human genome.
Chromosome - A linear end-to-end arrangement of genes and other DNA. An example is the Y chromosome which is the chromosome that determines the male gender. Human beings normally have 23 chromosome pairs. Chromosomes are found in the nucleus of the cell.
DNA - Deoxyribonucleic acid. Molecules that comprise the genetic makeup of all living organisms.
Junk DNA - DNA that does not cause the formation of genes. This type of DNA generally has very little or no function but is extremely useful for human identification.
Locus - (plural, loci) The specific place on a chromosome where a gene is located. An example of a locus on the Y chromosome would be DYS394.
Nucleotide bases - There are four important elements that make-up the informational component of DNA. These bases are Adenine (A), Guanine (G), Cytosine (C) and Thymine (T). These bases can exist in a myriad of combinations and make each segment of DNA unique.
Mitochondrial DNA (mtDNA) - DNA that is found in human cells but is not associated with the 23 chromosomes found in the nucleus. The mitochondrial DNA contains important information that can assist with questions of maternal inheritance.
Mutation - A process that produces a locus that has a different value from the preceding generation. For example, a father may have a value of 12 at Y chromosome locus DYS 394 and his known biological son may have a value of 13 at the same locus. If the relationship is truly known, then it can be assumed that the difference has occurred as a result of a mutation.
Mutation rate - A measurement of the number of times a mutation is observed at a specified locus within a given population over a specified period of time.
PCR - Polymerase Chain Reaction. A revolutionary technology that allows scientists to amplify specific regions of DNA that are of particular interest. Virtually invisible segments of DNA can be made visible using this process.
Primer - small bits of DNA that allow geneticists to analyze a particular genetic location. Primers define a marker.
Sex Chromosomes - The chromosomes that determine gender. There is only a single pair of sex chromosomes in the normal human genome. These chromosomes are named X and Y. Women have two X chromosomes and men have one X and one Y.
SNP - Single nucleotide polymorphism. A specific nucleotide position in the DNA that is different for different people within the population. For example, individual #1 has the sequence GGATGTTCAGATGC and individual #2 has the sequence GGATGTACAGATGC. The DNA position that is different may be helpful in distinguishing the two individuals.
STR - Short tandem repeats. Sections of DNA that have repeating motifs. These sections of DNA are often referred to as "junk" DNA. These repeating motifs may vary from one individual to another. STR results are generally reported as the number of repeat motifs that are observed at a single locus. The observed DNA sequence may be illustrated as GATAGATAGATAGATAGATAGATAGATAGATAGATAGATA. The value for this DNA sequence would then be reported as 10 repeats or as an allele value of 10 (See allele definition above). The DNA sequence before and after the repeat sequence is non-repeating and is not relevant to what is reported in the final result.
