Totipotent, Multipotent and Unipotent Cells
Laura Armstrong
Teacher
Contents
Recall Questions
This topic requires prior knowledge of stem cells from GCSE. You can test your knowledge below.
What is a stem cell?
An undifferentiated cell that can divide and develop into different types of specialised cells.
Where are stem cells found in the human body?
In embryos and certain adult tissues, such as bone marrow.
Why are stem cells important in medicine?
They can be used to treat diseases by replacing damaged or diseased cells (e.g. spinal injury, blood disorders).
Topic Explainer Video
Check out this @LauraDoesBiology video that explains totipotent, multipotent and unipotent cells or read the full notes below. Once you've gone through the whole note, try out the practice questions
What Is a Stem Cell? (A-Level Definition)
A stem cell is an undifferentiated cell capable of dividing indefinitely and differentiating into one or more types of specialised cells, depending on its potency.
Stem cells are crucial in:
- Growth and development in embryos.
- Repair and regeneration in adults.
- Therapies and regenerative medicine.
Types of Stem Cells by Potency
| Type | Definition | Example |
| Totipotent | Can differentiate into any cell type, including extraembryonic cells (placentaL cells). | Zygote and very early embryonic cells (up to 4–8 cell stage). |
| Pluripotent | Can become any body cell, but not extraembryonic tissues. | Embryonic stem cells (blastocyst stage). |
| Multipotent | Can develop into multiple, but related, cell types. | Bone marrow stem cells → blood cells (red blood cells, white blood cells and platelets). |
| Unipotent | Can produce only one specific cell type, but still has self-renewal ability. | Muscle stem cells → muscle fibres. |
Where Do We Find Stem Cells?
- Embryonic stem cells: Pluripotent cells from blastocysts.
- Adult stem cells: Multipotent or unipotent (e.g. bone marrow, skin).
- Induced pluripotent stem cells (iPS cells): Adult body cells genetically reprogrammed to become pluripotent.
Stem Cells and Differentiation
Stem cells become specialised through differential gene expression:
- In stem cells, all genes are switched on.
- As differentiation begins, some genes are activated, meaning the gene will be expressed, while others are switched off and the gene will not be expressed.
- This leads to production of specific proteins and cell structures → specialised function.
Key Terms
- Stem Cell: An undifferentiated cell with the ability to divide continuously and differentiate.
- Potency: The ability of a stem cell to differentiate into different cell types.
- Totipotent: Can form all body and placental cells.
- Pluripotent: Can form all body cells (not placental cells).
- Multipotent: Can form several cell types within a related group.
- Unipotent: Can form only one specialised cell type.
- Differentiation: Process where a cell becomes specialised in structure and function.
- Zygote: The fertilised egg cell.
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Exam Tip
Use the term ‘differentiate’, rather than ‘specialise’ that you may have used in GCSE.
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Describe the differences between totipotent, pluripotent, multipotent and unipotent stem cells and give one example of each. (4 marks)
- Totipotent stem cells can differentiate into any type of body cell, including placental cells (e.g. the zygote).
- Pluripotent stem cells can form any body cell, but not placental cells (e.g. embryonic stem cells).
- Multipotent stem cells can form a few closely related cell types (e.g. bone marrow stem cells → blood cells).
- Unipotent stem cells can produce only one specific cell type, but can self-renew (e.g. cardiac muscle stem cells).
Practice Question
Try to answer the practice question from the TikTok on your own, then watch the video to see how well you did!