Cell Differentiation and Specialisation

• Cells don’t look the same. They have different structures to suit their different functions.
• Differentiation is the process by which a cell changes to become specialised for its job.
• Most differentiation occurs as an organism develops.
• In most animal cells, the ability to differentiate is then lost at an early stage, after they become specialised. However, lots of plant cells don’t ever lose this ability.
• The cells that differentiate in mature animals are mainly used for repairing and replacing cells, such as skin or blood cells.
• Some cells are undifferentiated cells - they are called stem cells.
• Sperm cells are specialised for reproduction.
• The function of a sperm is basically to get the male DNA to the female DNA. It has a long tail and a streamlined head to help it swim to the egg. There are a lot of mitochondria in the cell to provide the energy needed. It also carries enzymes in its head to digest through the egg cell membrane.
• Nerve cells are specialised for rapid signalling.
• The function of nerve cells is to carry electrical signals from one part of the body to another. These cells (to cover more distance) and have branched connections at their end to connect to other nerve cells and form a network throughout the body.
• Muscle cells are specialised for contraction.
• The function of a muscle cell is to contract quickly. These calls are long (so they have space to contract) and contain lots of mitochondria to generate energy needed for contraction.
• Root hair cells are specialised for absorbing water and minerals.
• Root hair cells are cells on the surface of plant roots, which grow into long “hairs” the stick out into the soil. This gives the plant a big surface area for absorbing water and mineral ions from the soil.
• Phloem and xylem cells form phloem and xylem tubes, which transport substances such as food and water around plants. To form tubes, the cells are long and joined end to end. Xylem cells are hollow in the center and phloem cells have very few subcellular structures, so that stuff can flow through them.