1.4) Cellular Differentiation

Question 1

• What is ‘cellular differentiation’?

Answer 1

• ‘Cellular differentiation’
  ➞ process by which a cell expressed certain genes
  ↳ to produce protein characteristics for that type of cell.
  ➜ This allows a cell to carry out specialised functions.🧫

Question 2

• What is ‘selective gene expression’?

Answer 2

• Once a cell has differentiated,
  ➞ it only expresses the genes that code for the proteins specific to the workings of that particular cell 💼
• Many genes remain switched on,
  ➞ some genes become switched on,
  ↳ and unnecessary genes now become switched off. 🎚️

Question 3

• What are ‘meristems’?

Answer 3

• ‘Meristems’
  ➞ are regions of unspecialised cells in plants
  ↳ that can:
  ➜ divide (self-renew) and/or differentiate 🌿

Question 4

• What are ‘stem cells’?

Answer 4

• ‘Stem cells’
  ➞ are unspecialised cells in animals
  ↳ that can:
  ➜ divide (self-renew) by mitosis and/or differentiate into specialised cells of one or more types. 🐸

Question 5

• What are ‘embryonic stem cells’?

Answer 5

• Embryonic stem cells
  ➞ are found in the very early embryo (blastocyst)
  ➞ can differentiate into any cell type
  ➞ thus described as ‘pluripotent’

Question 6

• What are ‘tissue stem cells’?

Answer 6

• Tissue stem cells
  ➞ are involved in the growth, repair and renewal of cells found in that tissue
  ➞ can only differentiate into cells found in that particular tissue type
  ➞ thus described as ‘multipotent’
  ↳ (for example, blood tissue stem cells located in bone marrow can give rise to all types of blood cell - red blood cells, platelets, phagocytes and lymphocytes)

Question 7

• REVIEW QUESTIONS:
  ➞ 1 - Name two types of stem cells and comment on their differentiation potential.

➞ 2 - State where blood tissue stem cells are found within the body.

Answer 7

➞ 1 - Embryonic stem cells:
↳ they are ‘pluripotent’ and can differentiate into any cell type.
- Tissue stem cells:
↳ they are ‘multipotent’ and can differntiate into cells found in a particular tissue type.

➞ 2 - Bone marrow

Question 8

• What is the ‘therapeutic’ use of stem cells and can you write an example?

Answer 8

• ‘Therepeutic’ use of stem cells
  ➞ involves the repair of damaged or diseased tissues or organs
• EXAMPLE:
  ➞ If a muscle was damaged
  ↳ stem cells can be removed from patient and cultured in a lab🧪
  ➞ The new tissue cells
  ↳ can then be transported into the damaged muscle area.
• OTHER EXAMPLES:
  ➞ corneal repair
  ➞ regeneration of damaged skin

Question 9

• What is the ‘research’ use of stem cells and can you write an example?

Answer 9

• Stem cell ‘research’
  ➞ provides information on how cell processes
  ↳ such as cell growth, differentiation and gene regulation work.
• EXAMPLE:
  ➞ Stem cells
  ↳ can also be used as ‘model cells’
  ➜ to study how diseases develop or for drug testing.

Question 10

• What are the ethical issues surrounding stem cells?

Answer 10

• Use of embryonic stem cells
  ➞ can offer effective treatment for disease and injury
  ↳ however, it involves the destruction of embryos.

Question 11

• What are the pros and cons of ethical issues surrounding stem cells?

Answer 11

• PROS:
  ➞ can help treat and repair multiple cases of damaged/diseased tissues (i.e. corneal repair)
  ➞ improve pre-existing treatments at a healthcare level.
  ➞ better improve people’s medical conditions and quality of life.
• CONS:
  ➞ some may see the use of stem cells as the “destrcution of a potential human life”
  ➞ conflicts with religious views
  ➞ potentially dangerous in the stages of development (not ready yet)
  ➞ financial issues - not affordable.