- published: 10 Dec 2014
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An allele (UK /ˈæliːl/ or US /əˈliːl/) is one of two or more forms of a gene or a genetic locus (generally a group of genes). The form "allel" is also used, an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation. However, many variations at the genetic level result in little or no observable variation.
Most multicellular organisms have two sets of chromosomes, that is, they are diploid. These chromosomes are referred to as homologous chromosomes. Diploid organisms have one copy of each gene (and therefore one allele) on each chromosome. If both alleles are the same, they are homozygotes. If the alleles are different, they are heterozygotes.
A population or species of organisms typically includes multiple alleles at each locus among various individuals. Allelic variation at a locus is measurable as the number of alleles (polymorphism) present, or the proportion of heterozygotes in the population.
For example, at the gene locus for the ABO blood type carbohydrate antigens in humans, classical genetics recognizes three alleles, IA, IB, and IO, that determine compatibility of blood transfusions. Any individual has one of six possible genotypes (AA, AO, BB, BO, AB, and OO) that produce one of four possible phenotypes: "A" (produced by AA homozygous and AO heterozygous genotypes), "B" (produced by BB homozygous and BO heterozygous genotypes), "AB" heterozygotes, and "O" homozygotes. It is now known that each of the A, B, and O alleles is actually a class of multiple alleles with different DNA sequences that produce proteins with identical properties: more than 70 alleles are known at the ABO locus. An individual with "Type A" blood may be an AO heterozygote, an AA homozygote, or an A'A heterozygote with two different 'A' alleles.
Alleles and genes
8.1 Genes and Alleles
Allele - Point Of Origin (Full Album)
Chromosomes, genes, and alleles (IB Biology)
Alleles
Allele frequency
Multiple Alleles (ABO Blood Types) and Punnett Squares
Allele - Closer To Habit
Allele-Unknown
Allele - Immune
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I pick up the pieces and run away
Can now lay down, don't make a sound
Everyone needs a place to hide
To face the change that comes through lights
Burry the hopeless sound
Rise up and push it down
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Hell have to far behind us just take a [?]
Can now lay down, don't make a sound
Everyone needs a place to hide
To face the change that comes through lights
Afraid to brake into us rights
Just waiting just wake up
Just wake up
Can now lay down, won't make a sound
Everyone needs a place to hide
To face the change that comes through lights
Afraid to brake into us rights
Just waiting just wake up