BRAINCAKEMultiple Alleles
Multiple alleles means that a gene has more than two alleles in the population. However, each diploid individual can only carry two of them, one on each chromosome of a homologous pair, because it has only two copies of the gene locus.
Multiple alleles arise because different mutations of the same gene produce several versions of the gene. They often show a hierarchy of dominance, and some pairs may be codominant.
Example: the ABO blood group gene. The gene I codes for an enzyme that adds sugars to an antigen on the surface of red blood cells. There are three alleles:
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Key terms in this lesson
- codominance
- A type of inheritance in which two different alleles of a gene are both expressed in the phenotype of a heterozygote, rather than one masking the other.
More in Genetics and Variation
- Species
- Allopatric Speciation
- Sympatric Speciation
- Artificial Selection
- Codominance
- Codominance Genetic Crosses
- Multiple Allele Crosses - ABO Blood Groups
- Autosomal Linkage and Recombinant Offspring
All 41 lessons in Genetics and Variation · All OCR A-level Biology topics