Polygene

Polygene

A polygene, multiple factor, multiple gene inheritance, or quantitative gene is a group of nonallelic genes that together influence a phenotypic trait. The loci or identities of the nonallelic genes are frequently unknown to biologists, even though they are known to exist. The genes that contribute to type 2 diabetes are thought to be mostly polygenes.

Polygenic inheritance occurs when one characteristic is controlled by two or more genes (usually by many different genes) at different loci on different chromosomes. These genes are described as polygenes. Examples of human polygenic inheritance are height, skin colour and weight.

Each dominant allele has a small quantitative effect individually on the phenotype and these allelic effects are additive.

The frequency of the phenotypes of these traits follows a normal continuous variation distribution pattern. This shows that there are many possible types of allelic combination. When the values are plotted, a bell-shaped curve is obtained. The more genes are involved, the more continuous the variation and the distribution of the phenotypes.

Many human traits which are controlled by polygenes can be influenced to some extent by environmental factors. Examples include height in humans.Human height is determined by polygene, the different genes located at different chromosomes. Each of these genes has its own number of alleles. There is therefore a large number of possible combinations of alleles. Each gene has a small effect on height. The overall effect will depend on the additive effects of all the different alleles of the polygenes in a person's cells. As there are many different genes and many different alleles, there are many different possible combinations. These different combinations will produce people with many different heights. The result is continuous variation. Variation in human height is caused by genotype and can be influenced by the environment. For example, if a person has inherited a number of dominant alleles for tallness, he has the potential to grow tall. However if the diet is poor, for example, lacking in protein and calcium, the body cells do not have sufficient nutrients for maximuim development of the growth potential.


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • polygene — polygene. См. полиген. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Polygène — Un polygène est un groupe de gènes qui influence un trait du phénotype. Description Cette section est vide, insuffisamment détaillée ou incomplète. Votre aide est la bienvenue ! …   Wikipédia en Français

  • polygene — One of many genes that contribute to the phenotypic value of a measurable phenotype. * * * poly·gene päl i .jēn n any of a group of nonallelic genes that collectively control the inheritance of a quantitative character or modify the expression of …   Medical dictionary

  • polygene — n. one of a number of genes that together control a single characteristic in an individual. Each polygene has only a slight effect and the expression of a set of polygenes is the result of their combined interaction. Characteristics controlled by …   The new mediacal dictionary

  • polygene — noun Etymology: International Scientific Vocabulary Date: 1941 any of a group of nonallelic genes that collectively control the inheritance of a quantitative character or modify the expression of a qualitative character • polygenic adjective …   New Collegiate Dictionary

  • polygene — polygenic /pol ee jen ik/, adj. /pol ee jeen /, n. one of a group of nonallelic genes that together control a quantitative characteristic in an organism. [1940 45; back formation from polygenic; see POLY , GENE, IC] * * * …   Universalium

  • polygene — noun A group of nonallelic genes that act together to produce phenotype variations …   Wiktionary

  • polygene — poly·gene …   English syllables

  • polygene — pol•y•gene [[t]ˈpɒl iˌdʒin[/t]] n. gen any of a group of genes that act together cumulatively to produce a trait, as stature or skin pigmentation • Etymology: 1940–45; back formation from polygenic; see poly , gene, ic pol y•gen′ic ˈdʒɛn ɪk adj …   From formal English to slang

  • polygene — One of a number of genes, each of small effect, which together act to determine the phenotype of a quantitative trait. The result is continuous variation in the trait and a seemingly non Mendelian mode of inheritance. See: quantitative trait… …   Glossary of Biotechnology

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”