Key Stage 4
Meaning
A Recessive allele is an allele which can only be expressed in the phenotype when there are two copies of that allele.
About Dominant Alleles
- When a genotype includes one dominant allele and one recessive allele the physical appearance of the person will be based on the dominant allele.
- When there are two copies of the recessive allele the physical appearance of the person will be based on the recessive allele.
- In a Punnett Square or Genetic Cross Diagram dominant alleles are written with a capital letter while the recessive alleles are written with a lower case letter.
References
AQA
- Recessive alleles, page 217, GCSE Combined Science Trilogy; Biology, CGP, AQA
- Recessive alleles, page 265, GCSE Biology, CGP, AQA
- Recessive alleles, pages 36, GCSE Combined Science Trilogy 2, Hodder, AQA
- Recessive alleles/phenotypes, pages 209-213, GCSE Biology; Third Edition, Oxford University Press, AQA