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Gene order is the permutation of genome arrangement. A fair amount of research has been done trying to determine whether gene orders evolve according to a molecular clock (molecular clock hypothesis) or in jumps (punctuated equilibrium). By comparing gene orders in dissimilar organisms, scientists are able to develop a molecular phylogeny tree. [1]
A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species.It can be described as a variation (which may arise due to mutation or alteration in the genomic loci) that can be observed.
The earliest test takers were customers most often those who started with a Y-chromosome test to determine their father's paternal ancestry. These men often took part in surname projects . The first phase of the Genographic Project brought new participants into genetic genealogy.
In genetics, the coefficient of coincidence (c.o.c.) is a measure of interference in the formation of chromosomal crossovers during meiosis. It is generally the case that, if there is a crossover at one spot on a chromosome, this decreases the likelihood of a crossover in a nearby spot. [1] This is called interference.
A SNP array can also be used to generate a virtual karyotype using software to determine the copy number of each SNP on the array and then align the SNPs in chromosomal order. [10] SNPs can also be used to study genetic abnormalities in cancer. For example, SNP arrays can be used to study loss of heterozygosity (LOH). LOH occurs when one allele ...
By comparing the parental and double-crossover phenotypes, the geneticist can determine which gene is located between the others on the chromosome. The recombinant frequency is the ratio of non-parental phenotypes to total individuals. It is expressed as a percentage, which is equivalent to the number of map units (or centiMorgans) between two ...
A null allele is a gene variant that lacks the gene's normal function because it either is not expressed, or the expressed protein is inactive. For example, at the gene locus for the ABO blood type carbohydrate antigens in humans, [13] classical genetics recognizes three alleles, I A, I B, and i, which determine compatibility of blood transfusions.
Incomplete lineage sorting (ILS) [1] [2] [3] (also referred to as hemiplasy, deep coalescence, retention of ancestral polymorphism, or trans-species polymorphism) is a phenomenon in evolutionary biology and population genetics that results in discordance between species and gene trees.