Allele vs. Locus — What's the Difference?
By Tayyaba Rehman — Updated on September 22, 2023
Allele is one of the variant forms of a gene. Locus is the specific location of a gene on a chromosome. Both relate to genetics, but while alleles are gene variants, a locus denotes a gene's position.
Difference Between Allele and Locus
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Key Differences
An allele is a variant form of a gene. In many cases, genes have two alleles, one from each parent. For example, the gene responsible for eye color might have alleles that produce blue or brown eyes. The Locus, on the other hand, refers to the specific position or location of a gene (or an allele) on a chromosome.
Both alleles and loci (plural for locus) are fundamental concepts in genetics. While the allele provides information about the variant or type of a gene an individual possesses, the locus gives information about where that gene is located on the chromosome. Thus, while the allele might dictate the color of your eyes, the locus would tell you where the eye color gene resides on the chromosome.
It's essential to understand that while every locus has a gene, each gene can have multiple alleles. So, while a single locus might determine a particular trait, the alleles at that locus determine the variations of that trait. For instance, the locus responsible for eye color will always be in the same place, but the allele at that locus might vary, leading to blue, green, or brown eyes.
It's also worth noting that while the position of a locus remains constant on a chromosome, the allele present can vary among individuals. For instance, two people might share the same locus for hair color, but one might have the allele for brown hair while the other has the allele for blonde hair.
Comparison Chart
Definition
Variant form of a gene
Specific location of a gene on a chromosome
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Role in Genetics
Determines variations of a trait
Denotes the position of a gene
Variability
A gene can have multiple alleles
A locus remains constant on a chromosome
Example
Blue and brown eye color alleles
Locus for the eye color gene on a chromosome
Relation to Chromosome
Represents the type of a gene an individual has
Indicates the position of the gene
Compare with Definitions
Allele
A variant form of a gene.
Having a recessive Allele for a trait means both parents contributed that variant.
Locus
A fixed location on a chromosome.
Despite having different alleles, the Locus for a gene remains constant.
Allele
A specific DNA coding sequence.
The presence of an Allele can determine a specific characteristic in an organism.
Locus
The specific position of a gene on a chromosome.
Scientists identified the Locus responsible for a particular genetic disorder.
Allele
One of two or more versions of a gene.
The blue-eye Allele is less common than the brown-eye variant.
Locus
The site where a gene is found.
Mapping the human genome involves identifying each Locus.
Allele
The genetic information for a trait variant.
She inherited the Allele for red hair from her mother.
Locus
A locality; a place.
Allele
Represents the genetic diversity of a gene.
The Allele responsible for freckles can be dominant or recessive.
Locus
A center or focus of great activity or intense concentration
"the cunning exploitation of loci of power.
The insulation from normal American society" (Clifton Fadiman).
Allele
An allele (UK: , ; US: ; modern formation from Greek ἄλλος állos, "other") is one of two, or more, forms of a given gene variant. For example, the ABO blood grouping is controlled by the ABO gene, which has six common alleles.
Locus
(Mathematics) The set or configuration of all points whose coordinates satisfy a single equation or one or more algebraic conditions.
Allele
Any of the alternative forms of a gene or other homologous DNA sequence. Also called allelomorph.
Locus
The position that a given gene or genetic marker occupies on a chromosome.
Allele
(genetics) One of a number of alternative forms of the same gene occupying a given position, or locus, on a chromosome.
Locus
A place or locality, especially a centre of activity or the scene of a crime.
The cafeteria was the locus of activity.
Allele
One of two or more alternative forms of a gene that can have the same place on homologous chromosomes and are responsible for alternative traits.
Locus
(mathematics) The set of all points whose coordinates satisfy a given equation or condition. Category:en:Curves
A circle is the locus of points from which the distance to the center is a given value, the radius.
Allele
Either of a pair of Mendelian characters that may occur in an organism as a consequence of variation at one gene locus.
Locus
(genetics) A fixed position on a chromosome that may be occupied by one or more genes.
Allele
One of two alternate forms of a gene that can have the same locus on homologous chromosomes and are responsible for alternative traits;
Some alleles are dominant over others
Locus
A passage in writing, especially in a collection of ancient sacred writings arranged according to a theme.
Locus
A place; a locality.
Locus
The line traced by a point which varies its position according to some determinate law; the surface described by a point or line that moves according to a given law.
Locus
The scene of any event or action (especially the place of a meeting)
Locus
The specific site of a particular gene on its chromosome
Locus
The set of all points or lines that satisfy or are determined by specific conditions;
The locus of points equidistant from a given point is a circle
Locus
A reference point in genetics.
By understanding the Locus of a trait, researchers can study its inheritance patterns.
Locus
The genetic address for a gene.
The Locus provides a roadmap to find a specific gene.
Common Curiosities
Can there be multiple alleles at a single Locus?
Yes, a single locus can have multiple alleles, determining trait variations.
How is a Locus different from an Allele?
A locus refers to the specific location of a gene on a chromosome, while an allele is a variant of that gene.
Can a gene have only one Allele?
While many genes have multiple alleles, some might have only one common allele in a population.
Does each gene have a unique Locus?
Yes, each gene has a unique position or locus on a chromosome.
How do alleles contribute to genetic diversity?
Alleles represent different versions of a gene, leading to trait variations among individuals.
What happens if two alleles are at the same Locus?
An individual has two alleles at a given locus, one from each parent, determining the trait's expression.
Why is the Locus important in genetics?
Identifying the locus helps researchers pinpoint the location of genes on chromosomes.
Are all alleles equally common?
No, some alleles might be more common (dominant) while others are rarer (recessive) in a population.
Can two different genes have the same Allele?
No, alleles are specific to a particular gene.
What is an Allele?
An allele is a variant form of a gene.
Is the position of a Locus constant?
Yes, the position of a locus remains constant on a chromosome across individuals.
Can the Locus provide information about trait inheritance?
Yes, knowing the locus can help researchers study inheritance patterns of a trait.
Is every Locus associated with a visible trait?
No, not every locus (or gene) corresponds to a visible trait. Some might be related to internal processes.
How are diseases linked to alleles?
Some diseases are caused by specific alleles that lead to faulty protein production or function.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
