(a) Cellular Differentiation

• Cellular differentiation is the process by which a cell expresses certain genes to produce proteins characteristic for that type of cell. 

• This allows a cell to carry out specialised functions.

• Differentiation into specialised cells from meristems in plants; embryonic and tissue (adult) stem cells in animals.

  • Meristems are regions of unspecialised cells in plants that can divide (self-renew) and/or differentiate.

  • Stem cells are unspecialised cells in animals that can divide (self-renew) and/or differentiate.

  • There is no requirement to learn examples of differentiated animal and plant cells.

(b) Embryonic and tissue stem cells.

• Cells in the very early embryo can differentiate into all the cell types that make up the organism and so are pluripotent.

  • All the genes in embryonic stem cells can be switched on so these cells can differentiate into any type of cell.

• Tissue stem cells are involved in the growth, repair and renewal of the cells found in that tissue. 

  • They are multipotent.

  • Tissue stem cells are multipotent as they can differentiate into all of the types of cell found in a particular tissue type. 

  • For example, blood stem cells located in bone marrow can give rise to all types of blood cell.

• Therapeutic and research uses of stem cells.

  • The therapeutic uses of stem cells should be exemplified by how they are used in corneal repair and the regeneration of damaged skin.

• Therapeutic uses involve the repair of damaged or diseased organs or tissues.

  • Stem cells from the embryo can self-renew, under the right conditions, in the lab.

• Research uses involve stem cells being used as model cells to study how diseases develop or being used for drug testing.

  • Stem cell research provides information on how cell processes such as cell growth, differentiation and gene regulation work.

• The ethical issues of using embryonic stem cells.

  • Use of embryonic stem cells can offer effective treatments for disease and injury; however, it involves destruction of embryos.