What is Allele? Definition, Meaning & Example
An allele is one alternative form of a gene that controls a particular trait.
TL;DR: An allele is one alternative form of a gene that controls a particular trait.
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Allele: An allele is one alternative form of a gene that controls a particular trait.
Explanation
Each gene can have multiple alleles, different versions that produce different outcomes. For example, the gene for pea plant height has alleles for tall and short plants. An organism inherits two alleles for each trait, one from each parent. If both alleles are the same, the organism is homozygous. If alleles are different, the organism is heterozygous. Dominant alleles are expressed even in heterozygous individuals. Recessive alleles are only expressed if homozygous. Understanding alleles is essential for predicting traits in offspring and understanding genetic inheritance patterns.
Example
A pea plant may have alleles for both red and white flowers, but if the red allele is dominant, the plant flowers red.
Frequently Asked Questions
How many alleles can one person have for a trait?
Most people have two alleles for each trait, inherited from parents. Some traits have more than two alleles in the population, but each individual still has two. Genes on sex chromosomes may have only one allele in males.
What determines if an allele is dominant or recessive?
Dominance is determined by the protein product of the allele. If one allele produces sufficient protein to create the dominant phenotype, it is dominant. If two copies are needed for the trait, it is recessive. Dominance is not absolute - some alleles show incomplete dominance.
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