1.1.4 Cell Differentiation

Differentiation Process:

• Stem Cells: To become specialised, stem cells undergo differentiation to form specialised cells.
• Gene Activation: This involves switching some genes on or off to produce different proteins, allowing the cell to acquire specific sub-cellular structures needed for its function.

In Animals:

• Early Differentiation: Almost all cells differentiate at an early stage and then lose this ability.
• Mitosis: Most specialised cells can replicate through mitosis, producing identical cells.

• Red Blood Cells: Cells like red blood cells cannot divide because they lose their nucleus. They are replaced by adult stem cells that retain the ability to differentiate.
• Cell Division in Adults: In mature animals, cell division primarily occurs to repair or replace damaged cells since they undergo minimal growth.

In Plants:

• Continuous Differentiation: Many plant cells retain the ability to differentiate throughout their life.
• Final Position Differentiation: These cells differentiate once they reach their final position in the plant but can re-differentiate if moved to a new position.