MORE DETAILED DESCRIPTION: "Why Y?"  http://www.ucl.ac.uk/tcga/ScienceSpectra-pages/SciSpect-14-98.html

Definitions

Allele: One of the variant forms of a gene at a particular locus, or location, on a chromosome. Different alleles produce variation in inherited characteristics. For STR markers, each allele is the number of repeats of the short base sequence.

Base Pair: Two bases that form a "rung of the DNA ladder." A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the "letters" that spell out the genetic code. In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.

Chromosome: One of the threadlike "packages" of genes and other DNA in the nucleus of a cell.

DNA: The chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms.

DYS#: D=DNA, Y=Y chromosome, S=a unique DNA segment. A label for genetic markers on the Y chromosome. Each marker is designated by a number, according to international conventions. At present, virtually all the DYS designations are given to STR markers (a class often used in genetic genealogy).

Gene: The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.

Genome: All the DNA contained in an organism or a cell, which includes both the chromosomes within the nucleus and the DNA in mitochondria.

Locus: A point in the genome, identified by a marker, which can be mapped by some means. It does not necessarily correspond to a gene. A single gene may have several loci within it (each defined by different markers) and these markers may be separated in genetic or physical mapping experiments. In such cases, it is useful to define these different loci, but normally the gene name should be used to designate the gene itself, as this usually will convey the most information.

Marker: Also known as a genetic marker, a segment of DNA with an identifiable physical location on a chromosome whose inheritance can be followed. A marker can be a gene, or it can be some section of DNA with no known function. Because DNA segments that lie near each other on a chromosome tend to be inherited together, markers are often used as indirect ways of tracking the inheritance pattern of genes that have not yet been identified, but whose approximate locations are known.

Microsatellite: Repetitive stretches of short sequences of DNA used as genetic markers to track inheritance in families.

Mutation: A permanent structural alteration in DNA.

Short Tandem Repeats (STR): A genetic marker consisting of multiple copies of an identical DNA sequence arranged in direct succession in a particular region of a chromosome. Occasionally, one will mutate by the gain or loss of one repeat. (Also known as microsatellite)

Links

International Society of Genetic Genealogy (ISOGG) - The first society founded to promote the use of DNA testing in genealogy! With links to a wealth of genetic genealogy tools and information.

Contexo.Info A website about the foundations of molecular genetics and biology. An excellent site for those who are looking more details on DNA.

Time to Most Recent Common Ancestry Calculator by Bruce Walsh. The goal is to use genetic markers (here on the Y chromosome) to estimate the TMRCA, the Time to the Most Recent Common Ancestor (MRCA), which is how many generations the two Y chromosomes are from a common ancestor. This site explains the various models used to determine TMRCA.

The National Human Genome Research Institute - The National Human Genome Research Institute (NHGRI) created the Talking Glossary of Genetic Terms to help people without scientific backgrounds understand the terms and concepts used in genetic research.

Human Genome Project Information - The Human Genome Project (HGP) is an international effort to discover all the approximately 30,000 to 35,000 human genes (the human genome), make them accessible for further biological study, and determine the complete sequence of the 3 billion DNA subunits (bases).

Primer on Molecular Genetics - This primer was prepared by Denise Casey, Human Genome Management Information System, Oak Ridge National Laboratory, for the 1991-92 DOE Human Genome Program Report.

Primer on Molecular Genetics (pdf format) - This is an adobe version of the primer above.

Why Y? The Y Chromosome in the Study of Human Evolution, Migration and Prehistory - Neil Bradman and Mark Thomas of The Centre for Genetic Anthropology at University College London reveal the power of modern genetic analysis for exploring the role of fathers in human history.

Genetics & Genealogy: Y Chromosome DNA and the Y Line - by Thomas H. Roderick, PhD, Center for Human Genetics. A discussion of the Y-Chromosome and its role in DNA as tool for genealogists.

Short Tandem Repeat DNA Internet DataBase - While the use of STRs for genetic mapping and identity testing has become widespread among DNA typing laboratories, there is no single place where information may be found regarding STR systems. This web site is an attempt to bring together the abundant literature on the subject in a cohesive fashion to make future work in this field easier. Facts and sequence information on each STR system, population data, commonly used multiplex STR systems, PCR primers and conditions, and a review of various technologies for analysis of STR alleles have been included in this database.

GENEALOGY-DNA-L - This mailing list is for anyone with DNA (i.e., anyone!) who would like to discuss methods and share results of DNA testing as applied to genealogical research.

Genetic Genealogy and Telephone Tag - A simplified explanation of how Y-DNA mutates.