A scientist is growing human skin tissue in a laboratory to help treat patients with severe burns. The scientist uses embryonic stem cells rather than adult stem cells as the starting material. Explain why embryonic stem cells are a better choice than adult stem cells for this purpose, and describe what must happen to the stem cells before they can form skin tissue.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Severe burns can destroy large areas of skin. Scientists can grow replacement skin tissue in a laboratory using stem cells.
Model answer (4 marks)
Embryonic stem cells are totipotent, meaning they can differentiate into any cell type, so they can give rise to the keratinocytes and fibroblasts needed for skin.
Adult stem cells are lineage‑restricted; they can only become a limited range of cells and may not produce skin cells.
Before forming skin, the embryonic stem cells must first be induced to differentiate into skin‑specific progenitor cells.
They also need to proliferate by mitosis to generate enough specialised cells to build a functional skin tissue.
Adult stem cells are lineage‑restricted; they can only become a limited range of cells and may not produce skin cells.
Before forming skin, the embryonic stem cells must first be induced to differentiate into skin‑specific progenitor cells.
They also need to proliferate by mitosis to generate enough specialised cells to build a functional skin tissue.
Examiner tips
- Use the word ‘totipotent’ or ‘can differentiate into any cell type’ for embryonic cells. Mention the limited differentiation of adult stem cells. State ‘cell differentiation’ and ‘mitosis’ as the required processes.
- common_mistakes
- :
- Confusing totipotent with pluripotent. Saying adult stem cells can form any skin cell. Omitting the need for mitotic proliferation.
Mark scheme (4 marks)
- Embryonic stem cells can differentiate into any cell type (are unspecialised / are totipotent / can become any type of cell)
- Adult stem cells can only differentiate into a limited range of cell types, so they may not be able to form skin cells
- The stem cells must undergo cell differentiation to become specialised skin cells
- The stem cells must divide by mitosis to increase the number of cells / produce enough cells to form the tissue
Key terms in this question
embryonic stem cells · adult stem cells
Related
- Revision notes: Cell differentiation, growth and stem cells →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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