Key Area 4 - Cellular Differentiation Flashcards
Cellular Differentiation Definition
Cellular differentiation is the process by which a cell expresses certain genes to produce proteins that are characteristics for that type of cell. This allows cells to carry out specialised functions.
Differentiated cells are important in a multicellular organism because they are able to perform a specialised function in the body. However, specialisation comes at a cost. The cost is that the differentiated cells often lose the ability to make new copies of themselves.
Cellular Differentiation + Genes
Every cell in the body has all the genes necessary for constructing the whole organism. Genes can be switched off so a cell does not produce the protein that the gene codes for e.g insulin produced in pancreas cells only, not in brain or heart cells.
Meristems
Meristems are regions of unspecialised cells in plants that are capable of cell division.
They can:
* Self-renew through cell divison
* Differentiate
There are 2 types:
Apical (found on the tips of roots and shoots)
Lateral (found within the stem)
They are only found is certain parts of the plant such as the tip of roots and shoots and in between the xylem and phloem.
While animals stop growing in size once they become adults, cells produced by meristems ensure that plants continue to grow in height and width throughout their life:
* Meristems at the tips of roots provide a constant supply of new cells allowing roots to grow longer
* Meristems at the tips of shoots allow a plant to keep growing taller and spread wider
* Meristems between the xylem and phloem increase the width of a plant. These result in the annual growth rings in trees.
Stem Cells
Stem cells are unsepcialsied cells in animals that can:
* Self-renew by cell division
* Differentiate into specialisied cells
Embryonic Stem Cells
Cells in the very early embryo can differentiate into all the cell types that make up an organism. This is because all of their genes can be switched on. This is known as pluripotent.
Embryonic stem cells are important for growth.
Tissue Stem Cells
Tissue stem cells are involved in growth, repair and renewal of the cells found in the body tissues.
Tissue stem cells are multipotent. They can differentiate into all of the types of cell found in a particular tissue type e.g. blood stem cells in bone marrow only differentiate in all types of blood cells.
Tissue stem cells are found in a mature organism. Their function is to replenish differentiated cells that need to be replaced.
Research Uses of Stem Cells
- Model cells to study how diseases develop in drug-testing.
- Cell processes such as cell growth, differentiation and gene regulation.
Therapeutic Uses of Stem Cells
Therapeautic uses involve the repair of damaged or diseased organs or tissues.
- Repair of the cornea in the eye.
- Regenerating damaged skin.
- Bone marrow transplants
Ethical Considerations
Embryonic stem cells can self-renew, under the right conditions, in a lab. This means that embryonic stem cells can offer effective treatments for disease and injury. However, this involves the destruction of embryos.
