BharatNotes Allele
nounUsage in a UPSC answer
Just as a single gene may express itself through different alleles, India's federal idea is realised through competing institutional variants, each State adapting the constitutional template to its own demographic and developmental locus.
Synonyms
Word Family
allele (n), alleles (n pl), allelic (adj), allelomorph (n), allelomorphic (adj)
Root
Greek allos = other → allēl- = one another + morphē = form → German Allelomorph → Allel
Etymology
From German Allel, abbreviation of Allelomorph, from Greek allēl- ("one another," from allos, "other") + morphē ("form"); first used publicly by Frederick Soddy in 1913.
Memory Hook
Hear "a-LEAL" echo Greek allos = "other": an allele is an "other version" of the same gene, alternative forms standing side by side at one locus.
How This Word Works in UPSC Writing
One of the alternative forms a gene can take at a given locus on a chromosome. The vocabulary built on it is what questions test. An organism with two identical alleles at a locus is homozygous and with two different ones heterozygous; a dominant allele expresses itself in the heterozygote while a recessive one is masked, which is why a recessive disorder can appear in a child whose parents show no sign of it. Beyond simple dominance lie the cases that break the Mendelian pattern: codominance, where both alleles express fully, as in the AB blood group; incomplete dominance, giving an intermediate phenotype; and multiple alleles, where a gene has more than two forms in the population, the ABO system with its three alleles being the standard example even though any one person carries only two.
Don’t Confuse It With
An allele is a version of a gene, while the gene is the unit itself and the locus is its fixed address on the chromosome. Homozygous means carrying two identical alleles and heterozygous two different ones. A dominant allele is expressed in the heterozygote and a recessive one is masked there, so recessive means hidden, not rare. The genotype is the allele combination carried and the phenotype the trait actually observed.
Hindi Meaning
युग्मविकल्पी (yugmavikalpī) or एलील.
Common Questions
- What is an allele?
- One of two or more alternative forms of a gene occupying the same locus on a chromosome and governing the same trait.
- Does recessive mean rare?
- No. Recessive means the allele is masked in the presence of a dominant one, which says nothing about how common it is in the population.
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