Cell structure and organisation

• Eukaryotic cells


  Cells that contain a nucleus and membrane bound organelles
• Nucleus


  • Surrounded by a double membrane called the envelope
  • Contains pores that enable molecules to enter and leave
  • Contains chromatin
  • Contains a nucleolus which is the site of ribosome production
• Rough endoplasmic reticulum (RER)


  • Series of flattened sacs enclosed by a membrane with ribosomes on the surface
  • Folds and processes proteins made on the ribosomes
• Smooth endoplasmic reticulum (SER)


  • System of membrane bound sacs
  • Produces and processes lipids
• Golgi apparatus


  • Series of fluid filled, flattened & curved sacs with vesicles surrounding the edges
  • Processes and packages proteins and lipids
  • Produces lysosomes
• Mitochondria


  • Oval shaped, bound by a double membrane called the envelope
  • Inner membrane is folded to form cristae
  • Contains matrix with enzymes needed for respiration
• Centrioles


  • Hollow cylinders containing a ring of microtubules arranged at right angles
  • Involved in cell division
• Ribosomes


  • Composed of two sub-units
  • Site of protein production
• Lysosome


  • Vesicle containing digestive enzymes
  • Bound by a single membrane
• Prokaryotic cells (e.g. bacteria)

  • Cell wall - Rigid outer covering made of peptidoglycan
  • Capsule - Protective slimy layer
  • Plasmid - Circular piece of DNA
  • Flagellum - Tail-like structure that rotates to move the cell
  • Pili - Hair-like structures that attach to other bacterial cells
  • Ribosomes - Site of protein production
  • Mesosomes - Infoldings of the inner membrane containing enzymes for respiration

  
• Viruses


  Non-living structures consisting of nucleic acid (DNA or RNA) enclosed in a protective protein coat called the capsid, sometimes covered with a lipid layer called the envelope
• Cells of multicellular organisms are organised into tissues, tissues into organs and organs into systems