Cell Structure

• Prokaryote


  Unicellular organism which lacks a nucleus and other membrane-bound organelles
• Eukaryote


  Unicellular or Multicellular organism that includes a distinct membrane-bound nucleus and organelles
• Light microscope


  Light passes through a specimen, the light is then magnified using lenses
• Electron microscope


  Passing a beam of electrons through a specimen, the electrons are detected by a sensor which projects an image onto a screen
• Organelle


  Membrane-bound structure within a eukaryotic cell, which performs a specialised function
• Cell wall


  Outer layer of cell, provides structure and protection
• Cytoplasm


  Fluid, jelly-like inside of the cell that contains insoluble chemical substances, dissolved chemical substances, and suspended organelles
• Nucleus


  A large organelle bounded by a double membrane, containing most of the cell's DNA and code instructions for cell function
• Nucleolus


  A dark area found within the nucleus, production of new ribosomes
• Ribosomes


  Small dots found in the cytoplasm consisting of RNA and proteins where protein synthesis occurs
• Endoplasmic reticulum


  Networks of membrane-bound sacs that allow materials to be transported throughout the cell.

  • Rough ER has ribosomes attached and is involved in transporting proteins.
  • Smooth ER has no ribosomes and is involved in transport of other compounds such as lipids
• Mitochondria


  Organelles surrounded by two layers of membrane, outer layer is smooth, inner layer is rippled. Site of aerobic cellular respiration, generate power for the cell
• Golgi apparatus


  Stack of membrane-bound flattened sacs which bud off into vesicles, modify proteins and lipids and 'package' them for export from the cell
• Lysosome


  Spherical sacs surrounded by a single membrane, contain digestive enzymes to break down materials
• Centriole


  Barrel of nine bundles of microtubules, in animal and fungal cells organise spindle fibres during cell division
• Cilia


  Hair-like protuberances from the cell membrane, short and numerous, allow movement of the cell or movement of fluids across the cell surface in multicellular organisms, contain protein fibres that move relative to each other
• Chloroplast


  Large organelles bound by two layers of membrane, contain chlorophyll and are the site of photosynthesis in plant cells
• Fluid Mosaic Model


  Suggests that the membrane is composed of a bi-layer (two layers) of phospholipids, in which proteins and other molecules are suspended
• Cell membrane


  • Thin membrane that encloses the cytoplasm and controls the passage of substances into and out of the cell
• Phospholipids


  Macromolecule composed of two non-polar fatty acid tails (hydrophobic tails), joined to phosphate containing head (hydrophilic head)
• Proteins


  Biomolecules composed of amino acids
• Glycoprotein


  Recognition protein with sugar molecule attached in the golgi apparatus, recognise other cells as familiar or foreign
• Cholesterol


  Controls the fluidity of the membrane
• Flagella


  Long thread-like protuberance that allows movement of the cell, or movement of fluids across the cell surface
• Prokaryote Cell Shapes


  • coccus
  • bacillus
  • spirillum
• Prokaryote Cell Arrangement


  • pairs: diplo-
  • chains: strepto-
  • bunches: staphylo-
• Prokaryotic cell domains:

  Bacteria, archaea
• Eukaryotic cell domains

  Eukarya: animals, plants, fungi, algae
• Vacuole


  Large, fluid-filled storage sac in cytoplasm
• Peripheral protein


  Attached to outside of cell and provides cell structure. Can be enzymes or receptor (receives stimuli) proteins
• Integral proteins

  Embedded within membrane for channelling and transport of materials.

  • Carrier proteins
  • Channel proteins
  • Aquaporin
• Carrier protein


  Type of integral protein that is open on one side to control the enter/exit of ions e.g. sugars
• Channel proteins


  Type of integral protein that is open on both sides to control the transport of small ions and molecules

  E.g. Aquaporin channel protein for water molecules
• Capsule


  Outer layer of prokaryotic bacterial cell
• Plasmid


  Circular DNA molecule in Prokaryotic cells