A scientist is studying how cells in the human pancreas produce insulin, a protein hormone. Explain how the genetic information stored in a gene is used to produce a protein such as insulin.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Insulin is a protein hormone produced by specialised cells in the pancreas. It is essential for controlling blood glucose levels. Like all proteins, insulin is made following instructions encoded in DNA.
Model answer (5 marks)
1. A gene is a segment of DNA that encodes a specific amino‑acid sequence.
2. The gene is located in the nucleus of the pancreatic cell.
3. Transcription produces a messenger RNA (mRNA) strand that is a copy of the gene.
4. The mRNA exits the nucleus and is translated at the ribosome, where amino acids are joined together.
5. The resulting amino‑acid chain folds into the three‑dimensional shape of insulin, giving it its biological function.
2. The gene is located in the nucleus of the pancreatic cell.
3. Transcription produces a messenger RNA (mRNA) strand that is a copy of the gene.
4. The mRNA exits the nucleus and is translated at the ribosome, where amino acids are joined together.
5. The resulting amino‑acid chain folds into the three‑dimensional shape of insulin, giving it its biological function.
Examiner tips
- Use the exact terms: gene, DNA, nucleus, mRNA, ribosome, amino acids, protein structure.
- Show the flow: DNA → mRNA → ribosome → protein.
- Keep each point brief and separate with numbers or bullets.
Common mistakes
- Confusing DNA with mRNA as the messenger; forgetting the nucleus location.
- Lacking the step that amino acids are joined at the ribosome.
- Not linking the amino‑acid sequence to the final protein shape.
Mark scheme (5 marks)
- A gene is a section of DNA that codes for a specific amino acid sequence
- The DNA / gene is in the nucleus
- mRNA is made as a copy of the gene / mRNA carries the genetic information from the nucleus to the ribosomes
- Amino acids are joined together at the ribosomes
- The sequence of amino acids determines the structure / shape of the protein (insulin)
Key terms in this question
Related
- All OCR A-Level Biology B — Advancing Biology (H422) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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