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A polygene is a member of a group of non-epistatic genes that interact additively to influence a phenotypic trait, thus contributing to multiple-gene inheritance (polygenic inheritance, multigenic inheritance, quantitative inheritance [1]), a type of non-Mendelian inheritance, as opposed to single-gene inheritance, which is the core notion of Mendelian inheritance.
Epigenetic mechanisms. In biology, epigenetics is the study of heritable traits, or a stable change of cell function, that happen without changes to the DNA sequence. [1] The Greek prefix epi-(ἐπι-"over, outside of, around") in epigenetics implies features that are "on top of" or "in addition to" the traditional (DNA sequence based) genetic mechanism of inheritance. [2]
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 ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 28 January 2025. Science of genes, heredity, and variation in living organisms This article is about the general scientific term. For the scientific journal, see Genetics (journal). For a more accessible and less technical introduction to this topic, see Introduction to genetics. For the Meghan Trainor ...
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.
A gene can acquire mutations in its sequence, leading to different variants, known as alleles, in the population. These alleles encode slightly different versions of a gene, which may cause different phenotypical traits. [4] Genes evolve due to natural selection or survival of the fittest and genetic drift of the alleles.
These gene variants are called alleles. While some genes have only one allele because there is low variation, others have only one allele because deviation from that allele can be harmful or fatal. But most genes have two or more alleles. The frequency of different alleles varies throughout the population. Some genes may have alleles with equal ...
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.