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Allele frequency, or gene frequency, is the relative frequency of an allele (variant of a gene) at a particular locus in a population, expressed as a fraction or percentage. [1] Specifically, it is the fraction of all chromosomes in the population that carry that allele over the total population or sample size.
The frequency = + of normal alleles A increases at rate / due to the selective elimination of recessive homozygotes, while mutation causes to decrease at rate (ignoring back mutations). Mutation–selection balance then gives p B B = μ / s {\displaystyle p_{BB}=\mu /s} , and so the frequency of deleterious alleles is q = μ / s {\displaystyle ...
Genetic drift is the change in the relative frequency in which a gene variant occurs in a population due to random sampling. That is, the alleles in the offspring in the population are a random sample of those in the parents. And chance has a role in determining whether a given individual survives and reproduces.
Recently reported estimates of the human genome-wide mutation rate. The human germline mutation rate is approximately 0.5×10 −9 per basepair per year. [1]In genetics, the mutation rate is the frequency of new mutations in a single gene, nucleotide sequence, or organism over time. [2]
This process is often characterized by a description of the starting and ending states, or the kind of change that has happened at the level of DNA (e.g,. a T-to-C mutation, a 1-bp deletion), of genes or proteins (e.g., a null mutation, a loss-of-function mutation), or at a higher phenotypic level (e.g., red-eye mutation).
Genetic drift, also known as random genetic drift, allelic drift or the Wright effect, [1] is the change in the frequency of an existing gene variant in a population due to random chance. [ 2 ] Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation . [ 3 ]
Evolution is a change in the frequency of alleles in a population over time. Mutations occur at random and in the Darwinian evolution model natural selection acts on the genetic variation in a population that has arisen through this mutation. [2] These mutations can be beneficial or deleterious and are selected for or against based on that factor.
Therefore rare alleles spread through the population, pushing the gene pool toward an ideal equilibrium where every allele is equally common. [11] The major histocompatibility complex (MHC) is involved in the recognition of foreign antigens and cells. [12] Frequency-dependent selection may explain the high degree of polymorphism in the MHC. [13]