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Allele

Key Stage 4

Meaning

Alleles are different forms of the same gene.

About Alleles

A single gene, such as the gene for eye colour, may have several alleles such as blue eyes, brown eyes, green eyes...etc.
Alleles can be dominant or recessive.
Dominant alleles are expressed in the phenotype when there is only one copy of the allele. Whereas recessive alleles are only expressed in the phenotype when there are two copies.

References

AQA

Allele, pages 254-7, GCSE Biology; Student Book, Collins, AQA'
Alleles, page 217, GCSE Combined Science Trilogy; Biology, CGP, AQA'
Alleles, page 265, GCSE Biology, CGP, AQA'
Alleles, page 70, GCSE Combined Science; The Revision Guide, CGP, AQA'
Alleles, page 91, GCSE Biology; The Revision Guide, CGP, AQA'
Alleles, pages 199, 208-213, 234-235, GCSE Biology; Third Edition, Oxford University Press, AQA'
Alleles, pages 35, GCSE Combined Science Trilogy 2, Hodder, AQA'

Edexcel

Alleles, page 101, GCSE Biology, CGP, Edexcel
Alleles, pages 28-30, GCSE Combined Science; The Revision Guide, CGP, Edexcel
Alleles, pages 38-42, GCSE Biology; The Revision Guide, CGP, Edexcel
Alleles, pages 46-47, 64, GCSE Combined Science, Pearson Edexcel
Alleles, pages 61, 64-65, 88, GCSE Biology, Pearson, Edexcel
Alleles; codominant, page 68, GCSE Biology, Pearson, Edexcel
Alleles; multiple and missing, pages 68-69, GCSE Biology, Pearson, Edexcel

OCR

Alleles, pages 156-157, Gateway GCSE Biology, Oxford, OCR
Alleles, pages 48, 51, 54, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
Alleles, pages 66, 70, 73, Gateway GCSE Biology; The Revision Guide, CGP, OCR