BRAINCAKEGenetic Cross
Punnett squares are used to show genetic crosses. Dominant alleles are capitalised e.g. A, recessive alleles are shown in lower case e.g. a. For Co-dominant alleles, a capital letter and superscript is used e.g. ABO blood group which has multiple alleles: IA,IB (co-dominant) and IO (recessive). Gametes are shown as headings in a two-way table and the combinations shown in the cells.
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Key terms in this lesson
- Allele
- One of the different forms of a gene, arising from mutation, that occupies the same locus on homologous chromosomes.
More in Genetics and Variation
- Variation
- Body Mass
- Genetic Variation
- Continuous and Discontinuous Variation
- Sex Linkage
- Dihybrid Crosses
- Linkage
- Χ-squared Test
All 36 lessons in Genetics and Variation · All OCR A-level Biology topics