Phenylketonuria (PKU) is an inherited metabolic disorder.
It is caused by a gene mutation that produces a recessive allele, resulting in a non-functional enzyme, phenylalanine hydroxylase.
Explain the meaning of these genetic terms:
A parent who is heterozygous for PKU and a parent who has PKU are expecting a child. Draw a genetic diagram to calculate the probability that the child will have the condition. Use PPP for the normal allele and ppp for the allele for PKU.
Individuals with untreated PKU must strictly limit their intake of protein-rich foods, but can safely consume lipids and simple carbohydrates. Explain why.
Explain why stem cells programmed to differentiate into liver cells (hepatocytes) could be used as a treatment for PKU.
Why is it an advantage to use stem cells harvested from the patient (e.g., induced pluripotent stem cells) rather than from a donor?
97 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.