Explain the importance of cell differentiation in the development of…

The idea

A zygote divides by mitosis to form genetically identical cells, yet these become nerve, muscle, red blood and palisade cells. Cell differentiation is the process in which a cell develops the features it needs for a particular job, switching on the genes for the proteins that job requires. Its importance is that it produces specialised cells whose shape, organelles and protein content suit one function efficiently: a sperm cell gains a tail and many mitochondria for swimming, a root hair cell grows a long extension to absorb water and mineral ions, and a red blood cell loses its nucleus to carry more haemoglobin. Without differentiation an organism would have only unspecialised cells and could not carry out the range of functions a multicellular body needs. In MCQ items, link each structural feature to the function it serves.

What earns the marks

• Differentiation is the process by which a cell develops features suited to a specific function, involving switching on particular genes so specific proteins are made.
• Because cells differentiate into many types, a multicellular organism can carry out many different functions; unspecialised cells could not do this efficiently.
• Specialised cells show structures matched to function, for example a sperm cell with a tail and many mitochondria, or a root hair cell with a long extension for absorption.
• Differentiation allows efficient division of labour between cell types, so each tissue performs its role well rather than every cell attempting every job.
• Cells produced by mitosis from the zygote are genetically identical; differentiation explains how they become structurally and functionally different.

Common mistakes and how to put them right

• Thinking differentiation changes the genes a cell contains.

  Put it right: The genes stay the same, but different genes are switched on or off, so different proteins are made.

• Confusing differentiation with cell division.

  Put it right: Mitosis produces more cells, whereas differentiation changes a cell's structure and function.

• Assuming all cells in an organism are identical.

  Put it right: After differentiation they differ in shape, organelles and the proteins they produce.

Exam tips

• Read the whole option before choosing; eliminate options that claim genes are lost or changed during differentiation.
• Match each named specialised cell to a specific structural feature and the function that feature serves.
• If two options seem similar, choose the one that links structure to function rather than one that only names a cell type.