Search results
Results from the WOW.Com Content Network
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.
As of 2019, 260 imprinted genes have been reported in mice and 228 in humans. [10] Genomic imprinting is an inheritance process independent of the classical Mendelian inheritance. [11] It is an epigenetic process that involves DNA methylation and histone methylation without altering the genetic sequence.
Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]
European pied flycatcher Ronald Fisher in 1912. The sexy son hypothesis in evolutionary biology and sexual selection, proposed by Patrick J. Weatherhead and Raleigh J. Robertson of Queen's University in Kingston, Ontario in 1979, [1] states that a female's ideal mate choice among potential mates is one whose genes will produce males with the best chance of reproductive success.
Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. [2] The number of alleles an individual can have in a specific gene depends on the number of copies of each chromosome found in that species, also referred to as ploidy. In diploid species like humans, two full sets of ...
Recombination allows chromosomes to exchange genetic information and produces new combinations of genes, which increases the efficiency of natural selection and can be important in the rapid evolution of new proteins. [140] Genetic recombination can also be involved in DNA repair, particularly in the cell's response to double-strand breaks. [141]
If the genes of a gene family encode proteins, the term protein family is often used in an analogous manner to gene family. The expansion or contraction of gene families along a specific lineage can be due to chance, or can be the result of natural selection. [2] To distinguish between these two cases is often difficult in practice.
The candidate gene approach to conducting genetic association studies focuses on associations between genetic variation within pre-specified genes of interest, and phenotypes or disease states. This is in contrast to genome-wide association studies (GWAS), which is a hypothesis-free approach that scans the entire genome for associations between ...