Cells

• Chloroplast


  • Organelle, contains chlorophyll, absorbs light energy for photosynthesis, contains enzymes for photosynthesis
• Cell wall


  • Provides structure and protection, made from cellulose
• Permanent vacuole


  • Filled with cell sap, keeps the cell swollen
• Animal cells


  • May also have vacuoles, small and temporary
• Cell structures


  • Cytoplasm
  • Nucleus
  • Vacuole
  • Cell wall
  • Cell membrane
  • Chloroplasts
  • Mitochondria
• Eukaryotic cells


  • Have a nucleus, more structures surrounded by membranes
• Cytoplasm


  Jelly-like material, contains dissolved nutrients, salts and structures called organelles, where chemical reactions happen
• Nucleus


  Contains genetic material i.e. DNA, controls the cell's activities
• Cell membrane


  Permeable to some substances, controls the movement of substances in and out of the cell
• Mitochondria


  Organelles, contain enzymes for respiration, where most energy is released in respiration
• Ribosomes


  Small structures, protein synthesis occurs
• Mitochondria are visible with a light microscope but can't be seen in detail
• Ribosomes are only visible with an electron microscope
• Sperm


  • Head - contains genetic material for fertilisation in a haploid nucleus
  • Acrosome - contains enzymes so that a sperm can penetrate the egg
  • Middle piece - containing mitochondria, release energy needed to swim and fertilise egg
  • Tail - enables sperm to swim
• Sperm


  Smallest cells in the body, millions are made
• Egg cell


  • Cytoplasm - contains nutrients for growth of early embryo
  • Haploid nucleus - contains genetic material for fertilisation
  • Cell membrane - changes after fertilisation, no more sperm can enter
• Egg


  One of the biggest cells, only a few are made
• Differences between eukaryotic and prokaryotic cells

  • Size
  • Cell contents
  • Type of mitosis
• Bacterial cells


  • Single-celled, cells are prokaryotic - don't have a nucleus or any other structures surrounded by membranes
  • Chromosomal DNA - found loose in cytoplasm, not contained within a nucleus
  • Plasmid DNA - small, closed circles of DNA, present in cytoplasm, can move from one bacterium to another
  • Flagella - can have for movement, can rotate/move in a whip-like motion to move the bacterium
  • Cell wall - provides structure and protection
• Bacterial cells don't divide by mitosis, they copy themselves by binary fission
• Root hair cells


  • Large surface area - shape increases surface area to absorb more water and minerals
  • Thin cell wall - easy for minerals and water to pass through
  • Many mitochondria for active transport