Sickle-cell anaemia is a genetic disorder caused by a mutation in DNA. In this mutation, a single base substitution occurs in the gene that codes for the β\betaβ-globin polypeptide of the haemoglobin protein. Explain how this mutation causes a change in the structure of the protein produced. Use your knowledge of DNA, transcription, and translation.
The abnormal haemoglobin causes red blood cells to become rigid and sickle-shaped under low oxygen conditions, which can block small blood vessels. Suggest one symptom a person with sickle-cell anaemia may experience.
Sickle-cell anaemia can be treated using stem cells. Blood-forming stem cells from a healthy donor are transplanted into the patient's bone marrow. Explain why using stem cells from a healthy donor can treat sickle-cell anaemia.
72 exam-style questions on OCR GCSE Biology 1.2 What happens in cells (and what do cells need)?, covering 1.2.1 Structure of DNA, 1.2.2 Nucleotides and complementary bases, 1.2.3 Protein synthesis, 1.2.4 DNA structure and the proteins made, 1.2.5 Investigating enzymatic reactions, and 1.2.6 Mechanism of enzyme action. Each one has a worked solution and a mark scheme showing where the marks go.