BRAINCAKEDihybrid Crosses
These are used to show the inheritance of two different genes on two different chromosomes. Consider two pea plants - one with round, yellow seeds and one with green, wrinkled seeds. The allele for yellow seeds is dominant whilst the allele for green seeds is recessive. The allele for round seeds is dominant and the allele for wrinkled seeds is recessive. If a true-breeding, homozygous pea plant with yellow, round seeds is crossed with a true-breeding homozygous plant with green, wrinkled seeds, the parental genotypes are YYRR and yyrr. All of the offspring in the F1 generation are YyRr heterozygotes.
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Key terms in this lesson
- allele
- One of two or more alternative versions of a gene, occupying the same locus on homologous chromosomes.
- homozygous
- Having two identical alleles of a particular gene.
More in Genetics and Variation
- Genetic Variation
- Continuous and Discontinuous Variation
- Genetic Cross
- Sex Linkage
- Linkage
- Χ-squared Test
- Epistasis
- The Hardy-Weinberg Principle
All 36 lessons in Genetics and Variation · All AQA A-level Biology topics