Specialised cells

• All multicellular organisms like animal and plants begin life as a single fertilised egg cell, called a zygote
• The zygote divides into two cells, then 4, then 8, and so on until the adult body contains millions of cells
• All these cells must specialise to carry out their particula functions. Muscle cells contract, nerve cells carry impulses, etc.
• The process of cell specialisation is called differentiation
• Sperm cell - animal - function is to fertilise the egg and carry the father's genetic information to the egg - tail to help it swim
• Red blood cell - animal - carry oxygen from the lungs and deliver it to the body - large surface area, no nucleus
• Nerve cell - animal - carry electrical impulses from your brain to the rest of your body - many long brances to connect to other cells
• Muscle cells - shorten or contract to produce movement in body parts - contain many mitochondria for energy and proteins which make fibres contract
• Palisade cells - plant - photosynthesise and create sugars from the energy in light - large surface area, packed with chloroplasts
• Root hair cell - plant - allows the plant o absorb more water and minerals from the soil - has a large surface area and thin cell wall
• Xylem - plant - gives water and dissolved minerals to the plant and provides physical support - dead cells forming long tubes, coated with lignin
• Phloem - plant - transport and distribution of organic nutrients - has sieve plates, many mitochondria in companion cells