Cell differentiation

• Animal cell specialisation:

  Most animal cells are specialised. Also they have adaptations which help them to carry out their particular function. When cells become specialised, that is called differentiation.
• The job of a sperm cell is to join with an ovum (egg cell). We call that process fertilisation. During fertilisation, the genetic information of the ovum and the sperm combine. Like this...

  
• Sperm cell (part 1):

  Sperm cells contain their genetic information in the nucleus. However, sperm cells only contain half the genetic information of a normal adult cell. Sperm cells have a long tail which allows them to swim to the ovum. They are also streamlined to make this easier. Like this...

  
• Sperm cell (part 2):

  Sperm cells are packed full of mitochondria. These provide the energy needed for swimming. Sperm cells contain enzymes which allow them to digest their way through the outer layer of the ovum. Like this...

  
• The job of a nerve cell is to send electrical impulses around the body. Like this...

  
• Nerve cell (part 1):

  The axon carries the electrical impulses from one part of the body to another. The Myelin insulates the axon and speeds up the transmission of nerve impulses. The end of the axon has synapses. Synapses are junctions which allow the impulse to pass from one nerve cell to another. Like this...

  
• Nerve cell (part 2):

  Dendrites increase the surface area so that other nerve cells can connect more easily. Like this...

  
• Muscle cells can contract (get shorter). Like this...

  
• Muscle cell:

  Muscle cells contain protein fibres which can change their length. When a muscle cell contracts, these protein fibres shorten, decreasing the length of the cell. Muscle cells are also packed full of mitochondria to provide energy for muscle contraction. Muscle cells work together to form muscle tissue. Like this...

  
• Specialised cells are cells that have a particular structure and composition of sub-cellular structures.

  • The structural differences between different types of cells enables them to perform specific functions.
  • This allows organisms to operate more efficiently.
• Cells specialise by undergoing a process known as differentiation.

  • e.g. to develop into a nerve cell the cytoplasm and cell membrane of an undifferentiated cell must elongate to form connections over large distances.
  • Most animal cells (except stem cells) differentiate at an early stage during development to become specialised.
  • They then lose their ability to differentiate.
• The majority of plant cells never lose the ability to differentiate into specialised cell types.

  • They retain the ability to fully differentiate throughout the life of a plant.
• Diagram showing the differentiation of a human cell:

  
• Examples of Specialised Cells in Animals Table (part 1):

  
• Examples of Specialised Cells in Animals Table (part 2):

  
• Ciliated epithelial cells - the hair-like cilia beat to move mucus and any trapped particles:

  
• Nerve cells are long with extensions and branches to allow communication with other nerve cells or organs:

  
• Red blood cells are biconcave and contain no nucleus to maximise transport of oxygen:

  
• Sperm cells have a tail to enable the sperm to move:

  
• An egg cell contains a lot of cytoplasm rich in nutrients:

  
• Examples of Specialised Cells in Plants Table (part 1):

  
• Examples of Specialised Cells in Plants Table (part 2):

  
• Root hair cell have a large surface area to maximise absorption of water and minerals:

  
• Xylem cells lose their top and bottom walls to form a continuous tube through which water moves through:

  
• Palisade mesophyll cell contain many chloroplasts to help maximise photosynthesis: