CHARACTERISTICS OF PROKARYOTIC AND EUKARYOTIC CELLS by linzhengnd

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									CHARACTERISTICS OF
 PROKARYOTIC AND
 EUKARYOTIC CELLS
     CHAPTER 4
Cellular Characteristics
       Prokaryotes           Eukaryotes
        – Lack a nucleus       – Nuclear membrane
        – No organelles        – Possess organelles
        – 2 Domains:           – 1 Domain:
           • ARCHAEA              • EUKARYA
           • BACTERIA          – 4 Kingdoms:
                                  • ANIMALS
                                  • PLANTS
                                  • FUNGI
                                  • PROTOZOA



                                                      2
Prokaryotic Cells
     Sizes
      – 0.5 – 2µm (average)


     Shapes (3 basic)
      – Cocci
      – Bacilli
      – Spirals
     Arrangements
      –   Pairs = diplo
      –   Groups of 4 = tetrads
      –   Chains = strepto
      –   Clusters = staphylo

                                  3
Typical Prokaryotic Cell




                           4
Gram Positive Cell Wall
   Thick peptidoglycan
       – More physical
         strength
      Teichoic acids
       – Attachment of
         viruses

       – Molecular transport



                               5
Gram Negative Cell Wall
      Outer lipid membrane

       – Endotoxin


      Periplasmic space
       – Thin peptidoglycan

       – Enzymes/transporters
          • More chemical
            resistance


                                6
Other Cell Walls
       Acid Fast                    Wall deficient
        – Mycolic acid or other       – Mycoplasma
          waxy substance
        – Gram +ve wall below         – Some sterols




                                                       7
Cell Structures — Membrane
     Plasma membrane
      – Fluid mosaic
         • Proteins embedded
           in lipid
      – Phospholipid bilayer
         • Inner hydrophobic
           region

      – Chemical movement
         • Small, uncharged



                               8
Cell Structures — Membrane




                             9
Internal Cell Structures

       Cytoplasm
        – Watery medium
        – Enzymes
        – Cytoskeleton
       Ribosomes
        – 70S
       Nuclear region
        – DNA in higher
          concentration
                           10
Endospores

    Clostridium
    Bacillus


      Dipicolinic acid
       – Resist dehydration
       – Resist high
         temperatures



                              11
Cell Structures — External

     Flagellae
      – Single or many
      – Movement
      – 2 directions




                             12
Cell Structures — Axial filaments
      Axial Filaments
       – Spirochaetes
       – Similar structure to
         flagellae




                                    13
Cell Structures — Attachment

       Pili
        – Also used for DNA
          transfer


       Fimbriae




                               14
Cell Structures — Glycocalyx
     Capsule
      – Attachment
      – May limit
        penetration of
        some substances
        such as antibiotics,
        disinfectants
      – Virulence factor
     Slime Layer
      – Gliding substrate

                               15
Eukaryotic Cell Structure




                            16
Eukaryotic Cells
      Plasma membrane



      Cytoplasm



      Nucleus


                         17
Eukaryotic Organelles — Mt
      Mitochondria




                             18
Eukaryotic Organelles — Chloroplasts

       Chloroplasts




                                   19
Eukaryotic Organelles

       Ribosomes



       Endoplasmic Reticulum




                                20
Eukaryotic Organelles
       Golgi Apparatus      Peroxisomes




       Lysosomes            Vacuoles




                                            21
Cytoskeleton and Motility
    Cytoskeleton
    Flagellae




                            22
Motility — Cilia

        Cilia




                   23
Motility — Pseudopods

       Pseudopodia




                        24
Cell Walls

       Fungi



       Plants/Algae




                       25
    Endosymbiotic Theory
   Evidence:
    – DNA in Mt and
      chloroplasts

    – 70S ribosomes

    – No mitosis

    – Two membranes

                           26
Movement Across Membranes
   Diffusion
    – Molecules move down a concentration
      gradient
    – Size and charge are factors




                                            27
Osmosis

      Water movement
       – Conc. Gradient
       – Selectively
         permeable
         membrane limits
         movement of the
         solute




                           28
Active Transport

       Active transport




                           29
Endo/Exocytosis

       Engulfment of
        environmental
        substances/particles



       Expulsion of
        cytoplasmic
        contents

                               30

								
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