Importance of Cell Differentiation (Edexcel IGCSE Biology (Modular): Unit 1): Revision Note

Cell Differentiation & Specialised Cells

• The structural differences between different types of cells enable them to perform specific functions within an organism

• Cell differentiation is an important process by which a cell changes to become specialised

  • Cell differentiation is how cells develop the structure and characteristics needed to be able to carry out their functions

  • Specialised cells are those that have developed certain characteristics that allow them to perform particular functions. Developing these characteristics is controlled by genes in the nucleus

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

• When a cell differentiates, it develops a structure and composition of subcellular structures which enables it to carry out a certain function

  • E.g. to form a nerve cell the cytoplasm and cell membrane of an undifferentiated cell must elongate to form connections over large distances

When a cell differentiates, it develops a structure and composition that enables it to carry out a particular function.

Differentiation and development

• Stem cells are undifferentiated (unspecialised) cells that can divide by mitosis to form more stem cells or cells that go on to differentiate to become specialised cells

• As a multicellular organism develops, its cells differentiate to form specialised cells

  • In animals, most cells differentiate at an early stage of development

  • As a result, animal cells lose their ability to differentiate early in the life of the organism

• Specific cells in various locations throughout the body of an animal retain the ability to differentiate throughout the life of the animal

  • These undifferentiated cells are called adult stem cells and they are mainly involved in replacing and repairing cells, such as blood or skin cells

• Plants differ from animals in that many types of plant cells retain the ability to fully differentiate throughout the life of a plant, not just in the early stages of development

Examples of specialised cells

Ciliated cell

• Ciliated cells move mucus in the trachea and bronchi

• They have hair-like extensions called cilia, which beat to transport mucus and trapped particles toward the throat

Ciliated epithelial cells

Nerve cell

• Nerve cells conduct impulses and are long, allowing communication between different parts of the body and the central nervous system

• Their axons are covered in a fatty sheath that insulates and speeds up nerve transmission

A nerve cell

Red blood cell

• Red blood cells transport oxygen efficiently due to their biconcave shape, which provides a high surface area to volume ratio for oxygen diffusion

• Red blood cells are packed with the protein haemoglobin, which transports oxygen from the lungs to the rest of the body. Red blood cells do not have a nucleus, maximising space for haemoglobin to transport oxygen

Root hair cell

• Root hair cells absorb water and mineral ions from the soil

• Root hair cells have long extensions to increase surface area for maximum absorption, and their thin walls help water move quickly through them

Root hair cell

Palisade mesophyll cell

• Palisade mesophyll cells are found in the leaf and are adapted for photosynthesis

• Palisade mesophyll cells contain many chloroplasts

• The cells are column-shaped and tightly packed together beneath the upper epidermis of the leaf to maximise light absorption for photosynthesis

Palisade mesophyll cell