Differentiation and specialisation

• Cell Differentiation


  The process by which a cell changes to become specialised for its job
• Specialised cells


  • They have different structures to suit their functions
• Cell differentiation


  1. Cells develop specialised structures and functions as an organism develops

  2. Cells lose the ability to differentiate after they become specialised
• Specialised cells


  • Reproductive cells
  • Nerve cells
  • Muscle cells
  • Root hair cells
  • Xylem and phloem cells
• Undifferentiated cell


  Also called a stem cell
• Stem cells


  • They have the ability to differentiate into specialised cells
• Reproductive cells


  • Their function is to get the male DNA to the female DNA
  • They have a streamlined head to help it aim to the egg
  • They have enzymes in the head to digest through the egg cell membrane
  • They have mitochondria to provide the energy needed
• Nerve cells


  • Their function is to rapidly transmit electrical signals
  • They are elongated to cover more distance
  • They have branched connections to other nerve cells to form a network
• Muscle cells


  • Their function is to contract quickly
  • They have space to contract and contain lots of mitochondria to generate the energy needed for contraction
• Root hair cells


  • Their function is to absorb water and mineral ions from the soil
  • They grow into long "hairs" that stick out into the soil to increase the surface area
• Xylem and phloem cells

  • Their function is to transport substances around plants
  • Xylem cells are hollow in the centre and phloem cells have sieve-like structures to allow substances to flow through
• Chromosomes contain the genetic information that controls the development and functioning of cells
• Chromosomes


  • Most cells in the body contain 46 chromosomes
  • Chromosomes are structures that contain DNA
  • Each chromosome contains genes that control the development and functioning of cells
  • Chromosomes are inherited from both parents
• The cell cycle


  1. Cells reproduce in a series of stages

  2. The stage of the cell cycle determines what the cell is doing

  3. Multicellular organisms have cells at different stages of the cell cycle

  4. The end of the cell cycle results in two cells with the same genetic information
• You need to know the structure and function of specialised cells to understand how they relate to their function
• Phloem transports food substances from the leaves to growing parts of the plant
• The structure of a phloem cell makes it specialised for its function
• The structure of a root hair cell makes it specialised for its function