Question

Phenylketonuria (PKU) is a genetic condition caused by a defective enzyme

which results in abnormal metabolism. This condition is caused by an autosomal
recessive gene
If the normal gene is represented as P and the abnormal gene by p, use a
genetic inheritance diagram to show how a couple who do not have the
condition may still have a child that does have the condition
You should write down the genotypes of the parents and complete the diagram
to give types of gametes and type of offspring.

Answer 1

Step-by-step explanation:

Assuming both parents are carriers of the recessive PKU gene (Pp), the Punnett square below shows the possible genotypes and phenotypes of their offspring:

| P | p |

--|-----|-----|

P | PP | Pp |

--|-----|-----|

p | Pp | pp |

--|-----|-----|

1. PP: Normal phenotype, not a carrier
2. Pp: Normal phenotype, carrier of PKU
3. pp: PKU phenotype, affected by the disease

Therefore, there is a 25% chance that the child of two carrier parents will inherit two copies of the recessive allele (pp) and have PKU.