science

• Cell


  The smallest working unit of a living thing (organism)
• The word cell was first used by Robert Hooke in 1960
• Cells come in all shapes and sizes. Skin cells are very different from heart cells, which are very different from nerve cells, which are very different from muscle cells
• All living things are made of cells
• Types of cells


  • Unicellular (made of just one cell, for example bacteria)
  • Multicellular (made of many cells, for example humans)
• Characteristics of life


  • Reproduction - making new living things
  • Respiration - releasing energy from food
  • Response - reacting to the environment
  • Growth - increasing in number or size of cells
  • Excretion - getting rid of waste matter
  • Nutrition - requiring food
  • Movement - changing position
• Animal cell


  • Cell membrane - mostly made up of fat, protects the cell, allows substances in and out of the cell
  • Nucleus - carries genes which control the activities of the cell
  • Cytoplasm - watery fluid of salts and food in which cells float
  • Mitochondria - where energy is released from food in respiration
  • Ribosomes - make proteins, e.g. enzymes and hormones
• Plant cell


  • Cell membrane - mostly made up of fat, protects the cell, allows substances in and out of the cell
  • Nucleus - carries genes, which control the activities of the cell
  • Cytoplasm - watery fluid of salts and food in which organelles float
  • Mitochondria - where energy is released from food in respiration
  • Chloroplasts - contain chlorophyll for photosynthesis
  • Vacuole - a space in the cytoplasm where food and water are stored
  • Cell wall - made of cellulose, provides extra protection for the cell
• Plant cells have everything animal cells have