Higher Biology - Unit 1.4

​Unit 1.4

Cellular Differentiation

​Differentiation

• When a cell expresses genes that character​ise a certain type of cell, the cell has become differentiated

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• ​Once a cell has become differentiated it only expresses the genes that produce the proteins characteristic for this type of cell

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• Cells which are differentiated are specialised to carry out a specific function, making them important in a multicellular organism​

Specialised Cells

• Specialisation comes with a cost, that being that specialised cells become unable to make copies of themselv​es

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• Due to this problem, multicellular organisms must mantain unspecialised cells which can replenish these cells when needed​.

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• These cells are called stem cells​

Meristems

• Meristems are the region of unspecialised cells in plants

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• Meristems makes unspecialised cells which can become any specialised cel​l

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• Only found at the tip of the roots and shoots and in between the xylem and phloem

Stem Cells

• The region of unspecialised cells in animals

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• There are 2 types; Embryonic and Tissue (adult)

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• Used theraputically to repair damaged, or diseased organs

Embryonic Stem Cells

• Found in an early embryo, and are able to divide continuously

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• All genes in an embryonic stem cell can be​ expressed, therefore they can give rise to all types of cell

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• They are essential for growth​

Tissue Stem Cells

• Found in mature organisms

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• Their function is to replenish differentiated cells that need to be replaced

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• T​hey are called multipotent, meaning they can only give rise to the limited range of cells of their particular tissue type

Multiple Choice

Which of the following cells are multipotent?

• Embryonic stem cells

• Tissue stem cells

​List of Terms

Cellular differentiation - The process of specialisation when an undifferentiated cell expresses certain genes fitting of its characteristics

Embryonic stem cell - Stem cell from an embryo that can divide and become any type of cell

Tissue stem cell - Stem cell from tissue that can divide and differentiation to become cells of that tissue

Meristem - The region of unspecialised cells in plants where photosynthesis occurs

Stem cells - The region of unspecialised cells in animals

Multipotent - Refers to Tissue stem cells which can only give rise to a limited range of cells of their particular tissue type

Pluripotent - Refers to Embryonic stem cells which can differentiate into all the cell types​

​END OF KEY AREA