BRAINCAKECodominance Genetic Crosses
Genetic crosses involving codominant alleles are set out in the same way as other monohybrid crosses, but each genotype gives a different phenotype, so the phenotypic ratio matches the genotypic ratio.
Take coat colour in shorthorn cattle: CRCR red, CWCW white, CRCW roan.
Cross 1: red × white
Parents: CRCR × CWCW
Gametes: all CR and all CW
Offspring: all CRCW, so all roan.
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Key terms in this lesson
- genotype
- The genetic constitution of an organism, i.e. the particular combination of alleles it possesses.
- phenotype
- The observable characteristics of an organism, resulting from the interaction of its genotype with the environment.
More in Genetics and Variation
- Species
- Allopatric Speciation
- Sympatric Speciation
- Artificial Selection
- Codominance
- Multiple Alleles
- Multiple Allele Crosses - ABO Blood Groups
- Autosomal Linkage and Recombinant Offspring
All 41 lessons in Genetics and Variation · All AQA A-level Biology topics