Ultrastructure of prokaryotic cells

• Prokaryotic Cell

  
• They are similar to eukaryotic cells because they have:

  • A plasma membrane
  • Cytoplasm
  • Ribosomes for assembling amino acids into proteins
  • DNA and RNA
• They are different from eukaryotic cells as they:

  • Are much smaller
  • Have a much less well- developed cytoskeleton with no centrioles
  • Do not have a nucleus
  • Do not have membrane- bound organelles such as mitochondria, endoplasmic reticulum, chloroplasts or golgi apparatus.
  • Have a wall that is made of peptidoglycan and not cellulose.
  • Have smaller ribosomes
  • Have naked DNA that's not wound around histone proteins but floats free in the cytoplasm, as a loop (not linear chromosomes).
• Comparison between eukaryotic and prokaryotic cells:

  
• Some prokaryotic cells also have:

  • A protective waxy capsule surrounding their cell wall
  • Small loops of DNA, called plasmids, as well as the main large loop of DNA.
  • Flagella- long whip-like projections that enable them to move. The structure of these flagella differs from that of eukaryotic undulipodia.
  • Pili- smaller hair-like projections that enabe the bacteria to adhere to host cells or to each other, and allow the passage of plasmid DNA from one cell to another.