1.1.4 Cell differentiation

• What happens as a cell differentiates?

  ● It acquires different sub-cellular structures

  ● To enable it to carry out a certain function

  ● So it has become a specialised cell
• When do animal cells differentiate?

  ● Most types differentiate at an early stage (embryo development)

  ● In mature animals, cell division mainly restricted to repair and replacement (eg. new blood / skin cells)
• When do plant cells differentiate?

  Many types retain the ability to differentiate throughout life.
• Why is cell differentiation important?

  ● As an organism develops, cells differentiate to form different types of cells

  ● Specialised cells make different parts of the body / tissues / organs
• Why is this statement wrong?

  “All cells are differentiated in adults.”

  Stem cells remain in certain parts of the body, eg. bone marrow. These are undifferentiated cells that can differentiate into other cell types, eg. blood cells.
• Explain the role of differentiation in the development of root hair cells which allows them to carry out their specific function in plants. (3)

  ● Differentiation determines cell shape / development of specific

  sub-cellular structures

  ● Grow extensions to give a large surface area for rapid uptake of water by osmosis

  ● Develop many mitochondria to release energy for active transport of mineral ions
• Compare the process of

  differentiation in animals

  and plants. (2)

  ● Differentiation in animals occurs early in development / at an early stage

  ● Plant cells retain the ability to differentiate / have unspecialised cells capable of forming any cell required when mature