Oculocutaneous albinism type 1 (OCA1) is an inherited genetic condition.
It is caused by a mutation in the tyrosinase gene, which is required for the production of the pigment melanin. This mutation produces a recessive allele.
Explain the meaning of these terms:
If a person has two mutated alleles for OCA1, they will produce little to no melanin in their skin, hair, and eyes.
Why does a person need to inherit two mutated alleles to have OCA1?
Why does this condition cause individuals to have highly sensitive skin that burns extremely easily in sunlight?
Two people are heterozygous carriers for OCA1 and are expecting a baby.
Complete the Punnett square to work out the probability that the baby will have OCA1. Let AAA be the normal allele and aaa be the mutated allele for OCA1.
| AAA | aaa | |
|---|---|---|
| AAA | ||
| aaa |
State the probability that the baby will develop OCA1.
Scientists are investigating the use of stem cells to treat skin damage in patients with severe pigment disorders. Why might stem cells be able to regenerate functional, melanin-producing skin tissue?
State two reasons why medical treatments, such as new cell therapies or drugs, are tested on animals or laboratory-grown cells before being trialled on humans.
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.