1. Prokaryotes vs. Eukaryotes

3. I. Structure, function, and reproduction of prokaryotes
        A.  Most prokaryotes are unicellular.          
1.Some species form aggregates of two or more individuals.
  B.  Three (3) common shapes:  cocci (round); bacilli (rod); helical (spiral)

4. The world of prokaryotes
C.  They’re everywhere!
                       
Collective prokaryote biomass outweighs all eukaryotes combined by at least tenfold. 
They exist almost everywhere, including places where eukaryotes cannot.
Most prokaryotes are beneficial; we couldn’t live without them.  (e.g. Nitrogen-fixing bacteria)

6. Lyme disease:
Caused by a spirochete

7. Some cause illness à bubonic plague, diphtheria, salmonella
Approximately 5000 species have been identified.  Estimates of prokaryote diversity range from 400,000 to 4,000,000 species.            
D.  Bacteria and Achaea are the two main branches of prokaryote evolution
Achaea are thought to be more closely related to eukaryotes than to bacteria.

8. E. Most prokaryotes secrete sticky substances that form a protective layer and enable them to adhere to substrates.
   1.  The sticky protective layer secreted by prokaryotes is called the capsule.
2. Some prokaryotes adhere to substrates using Pili.  (Pili are thin, protein tubes originating from the cytoplasmic membrane)
                   a.  Some Pili are specialized for DNA transfer. This process is called conjugation; note for later in class.            

9. F. Almost all prokaryotes have cell walls external to
F.  Almost all prokaryotes have cell walls external to the plasma membrane.
1. Cell walls maintain cell shape.
2. Cell walls are composed of peptidoglycan.(a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria, forming the cell wall)

10. G. Cellular and genomic organization of prokaryotes is
G. Cellular and genomic organization of prokaryotes is different from that of eukaryotes
                       
1.Prokaryotes have no nucleus.
  2. The nucleoid region in a prokaryotic cell consists of a concentrated mass of DNA. This mass of DNA is usually one thousand times less than what is found in a eukaryote.

11. Specialized membranes of prokaryotes
nucleoid N

12. Prokaryotic cells
Diagram

13. Components of a prokaryote
Cytoplasm
Ribosomes
Nuclear Zone
DNA
Plasmid
Cell Membrane
Mesosome
Cell Wall
Capsule (or slime layer)
Flagellum

15. Lipopolysaccharide layer
Gram Positive
Peptidoglycan
Plasma membrane
Gram Negative
Lipopolysaccharide layer
Outer membrane
Peptidoglycan
Plasma membrane

19. PROCARYOTES
Photosynthesis evolved early in prokaryotic life
                       
Cyanobacteria started to produce O2 about 2.7 billion years ago
Contrasting hypotheses for the taxonomic distribution of photosynthesis among prokaryotes.

20. Heliobacteria: Causes stomach ulcers

21. - Parasitic; survive only within cells of animals
 2.  Chlamydias
- Parasitic; survive only within cells of animals
 - Some cause STDs e.g. Chlamydia

22.  3.  Spirochetes
      - Helical heterotrophs
     - Some cause STDs e.g. syphilis

23. Mycoplasma shown covering a human cell; some species of mycoplasmas cause walking pneumonia

24.  5.  Cyanobacteria
         - Oxygenic photosynthesis, and chloroplasts evolved from them.

25. Ecological impacts of prokaryotes
           
A.  Prokaryotes are links in the recycling of chemical elements
B.  Many prokaryotes are symbiotic (2 organisms living in direct contact with each other).
                    
Mutualism – both symbiotic organisms benefit
                   - e.g. Nitrogen-fixing bacteria like Rhizobium: plant obtain organic nitrogen, Rhizobium gets energy in the form of sugars that the plant produces.

26. Are all prokaryotes disease producing germs?
53.10
Are all prokaryotes disease producing germs?
Without prokaryotes ecosystems would collapse!

27. Humans use prokaryotes in research and technology
Humans use prokaryotes in research and technology
                       
Examples:
Sewage treatment
Bioremediation
Chemical & Medical production
Research (genetic engineering, etc.)

29. Eukaryotic and Prokaryotic Cells
Prokaryote = without a nucleus
Eukaryote = with a nucleus

30. EUKARYOTE Diagram

31. Components of a Eukaryote
Cytoplasm
Nucleus with Nucleolus
Mitochondria
Chloroplast
Ribosomes
Rough Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Golgi body
Vacuoles

32. Components of a Eukaryote continued
Lysosomes
Cytoskeleton
Centriole
Cilium and Flagellum
Microvillus
Cell membrane
Cell Wall

33. Comparing Prokaryotic and Eukaryotic Cells
Prokaryotes
Eukaryotes
Have Organelles
Have a
nucleus
Have membranes surrounding organelles
Have cell wall
or membrane
Are mostly bacteria
Include all plant and animal cells
Have DNA
Have cytoplasm

34. Summary of the differences!
Prokaryotic Cells
Eukaryotic cells
small cells (< 5 mm)
larger cells (> 10 mm)
always unicellular
often multicellular
no nucleus or any membrane-bound organelles
always have nucleus and other membrane-bound organelles
DNA is circular, without proteins
DNA is linear and associated with proteins to form chromatin
Ribosomes are small (70S)
Ribosomes are large (80S)
no cytoskeleton
always has a cytoskeleton
cell division is by binary fission
cell division is by mitosis or meiosis
reproduction is always asexual
reproduction is asexual or sexual