Prokaryotic and Eukaryotic Cells

• Life is an emergent property of a particular arrangement of certain molecules
• The basic unit of life is the cell
• Prokaryotic cells have no true nucleus
• Eukaryotic cells have a true nucleus
• Unicellular organisms: each cell carries out all life processes
• Multicellular organisms are made up of many cells, with different cells specialized to perform different functions
• Cells are small because they require a high surface to volume ratio to exchange materials with their environment
• Bacterial Cells:

  • No true nucleus
  • No endoplasmic reticulum
  • No Golgi apparatus
  • No mitochondria
  • No chloroplasts
  • No vesicles or vacuoles
  • No centrosome
• Animal Cells:

  • No cell wall
  • No plasmodesmata
  • No chloroplasts
  • No central vacuole
• Plant Cells:

  • No centrosome
  • No lysosomes
  • Cell wall made of cellulose
• Fungal Cells:

  • Eukaryotic
  • Cell wall made of chitin
  • Pores between cells
  • No plasmodesmata
  • No centrosome
  • No chloroplasts
• Bacterial cell (Prokaryotic cell: Bacterium):

  • Plasma membrane (boundary between cell and environment)
  • Cytosol (complex mixture of enzymes and many other molecules and water)
  • Ribosomes (site of protein synthesis)
  • Plasmid (accessory genetic information)
  • Capsule (sticky, protects cell from attack & dehydration)
  • Nucleoid (genetic information, made of a single loop of double-stranded DNA)
  • Cell wall (rigid, gives cell shape)
  • Flagellum (rotates to provide mobility)
• • Phospholipid bilayer has a polar head and non-polar tails, is a fluid bilayer, relatively impermeable to polar molecules
  • Non-polar molecules (O2, CO2, lipids) diffuse through freely
  • Smaller polar molecules (H2O, ethanol) diffuse through much more slowly
  • Larger polar molecules (glucose) diffuse through hardly at all
  • Phospholipid bilayer is a semipermeable membrane
  • Channel protein allows certain proteins to pass through the phospholipid bilayer with no control of direction of movement
  • Carrier protein picks up molecule and releases on the other side
• Animal Cell:

  • Mitochondria: generates ATP for cell
  • Cytosol: the liquid in the cell
  • Smooth endoplasmic reticulum: synthesis of lipids, destruction of drugs and toxins
  • Rough endoplasmic reticulum: synthesis of proteins to be packaged
  • Golgi apparatus: packages proteins from rough er
  • Lysosome: vacuole of digestive systems
  • Vacuole: larger membrane sack of material
  • Flagellum: whips to provide mobility
  • Vesicle: small membrane sack of material
  • Ribosome: makes proteins
• Mitochondria:

  • Matrix
  • Outer membrane: similar to plasma membrane
  • Inner membrane
  • Loop of DNA
  • Ribosome
• Plasmodesmata:

  • Allows passage of cytosol from cell to cell
• Eukaryotic cell (Plant):

  • Contains chloroplasts for photosynthesis
  • Central vacuole for storage and turgor
  • Mitochondrion
  • Thylakoid provides a membrane for photosynthesis
  • Turgor: stiffness caused by water pressure
• Animal Cell Nucleus:

  • Chromatin: several diffuse chromosomes
  • Nuclear envelope: separates the nucleus from the cytoplasm
  • Nucleolus: site of assembly of ribosomes
• Plasma membrane:

  • Extracellular matrix: structural support to tissues
  • Cholesterol: helps maintain membrane fluidity
  • Receptor protein: responds to a specific chemical
  • Identification marker: allow cells to be recognized
  • Tight junction proteins: hold cells together
• Cytosis: transport via folding of a membrane

  Endocytosis: entering the cell via cytosis

  Exocytosis: exiting the cell via cytosis
• Animal cell:

  • Centrosome: organizes cytoskeleton
  • Pilus (pili): a thin fibers on the surface of bacteria
  • Cytoskeleton: cell shape, cell movement intracellular transport
• Generally how many layers of phospholipids make up the cell membrane?

  Two
• What structure allows molecules to move in and out of the cell?

  Cell membrane