Allele: One member of a pair or series of genes that occupy a specific position on a specific chromosome.

Centimorgan: A unit of crossover frequency in linkage maps of chromosomes equal to one hundredth of a morgan.

DNA polymorphism: A condition in which one of two different but normal nucleotide sequences can exist at a particular site in a DNA molecule.

Gamete: A reproductive cell having the haploid number of chromosomes, especially a mature sperm or egg capable of fusing with a gamete of the opposite sex to produce the fertilized egg.

Genetic distance: A measure of the allelic substitutions per locus that have occurred during the separate evolution of two populations or species. The distance between linked genes in terms of recombination frequency or map units (i.e. centimorgan).

Genome:  The total genetic content contained in a haploid set of chromosomes in eukaryotes, in a single chromosome in bacteria, or in the DNA or RNA of viruses.  An organism's genetic material.

Genotype: The combination of alleles located on homologous chromosomes that determines a specific characteristic or trait.

Genotyping: the process of determining the genotype of an individual with a biological assay. Current methods of doing this include PCR, DNA sequencing, and hybridization to DNA chips or beads. The technology is intrinsic for test on father-/motherhood and in clinical research for the investigation of disease-associated genes.

Haplotype: A set of alleles of closely linked loci on a chromosome that tend to be inherited together.

Loci: Plural of locus.

Locus: The position that a given gene occupies on a chromosome.

Meiotic recombination: The formation and repair of double strand breaks through a double Holliday junction intermediate that results in the equal exchange of genetic material between non-sister chromatids in a pair of homologous chromosomes. These reciprocal recombinant products ensure the proper segregation of homologous chromosomes during meiosis I and create genetic diversity.

Polymerase chain reaction (PCR):  A technique for amplifying DNA sequences in vitro by separating the DNA into two strands and incubating it with oligonucleotide primers and DNA polymerase. It can amplify a specific sequence of DNA by as many as one billion times and is important in biotechnology, forensics, medicine, and genetic research.

Physical distance:  the distance in base pairs, i.e. Distance between two markers.  The extremely high resolution allows fir easier identification of mutations. 

 
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