1. Polydactyly is caused by a dominant allele, D. The recessive allele of the gene is represented by d. Use one genetic diagram to show the inheritance of the polydactyly gene by R and S.
P generation Father (P) Mother(Q)
Phenotype Polydactyly Normal
Genotype Dd dd
Gamete D d d d
Fertilization
Punnett Square for F1 generation
F/M
d
d
D
Dd
Dd
d
dd
dd
Phenotypic ratio: 1:1
Affected: Unaffected
Offspring: Offspring
Genotypic ratio: 1:1
Dd: dd
SC
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