1. Prokaryotes and Origin of Metabolic Diversity
AP Biology
Crosby High School

2. A World of Prokaryotes Your mouth They are more infamous than famous
Two types
Archaea: Origin from the first cell
Bacteria: More recent
Differ in structural, biochemical, and physiological
Carl Woese

3. Cell Shapes Cocci Bacillus Spirilla and Spirochetes Size range
Spherical
Bacillus
Rod
Spirilla and Spirochetes
Size range
1-5 µm
Largest is .75 mm

4. Bacterial Cell Walls Composed of peptidoglycans
Form a capsule to protect from host defenses
Gram stains
Gram-positive (Purple)
Simpler walls
Large amt. Peptidoglycans
Gram-negative (Pink)
Contain lipopolysaccharides
Generally more threatening

5. Prokaryotic Motility Flagella Spirochetes Slime Secretions
1/10 width of Eu.
Not covered by membranous extension
Spirochetes
Flagella-like connected to basal motor
Corkscrew motion
Slime Secretions
Taxis: Movement toward or away from stimulus

6. Cellular and Genomic Organization
Lack Compartmentalization
1/1000 as much DNA as Eu.
May contain Plasmids
Can survive w/o Plasmids
Give resistance to antibiotics
Replicate independently of genophore

7. Prokaryotic Reproduction
Binary Fission
Gene transfer
Transduction: Viruses transfer genes
Conjugation: Direct transfer of genes
Transformation: Takes genes from surrounding environment
Generations take minutes – hours

8. Growth and Protection Geometric “Growth” Limitations of growth
Nutrient exhaustion
Metabolic waste
Endospore
Cell Replicates its chromosomes
One copy is surrounded by a durable wall
Autoclaves needed to kill endospores

9. Prokaryotic Nutrition
Photoautotrophs
Light and Carbon Dioxide
Cyanobacteria
Chemoautotrophs (Pro. Only)
Carbon dioxide for Carbon source
H2S, NH3, Fe2+
Photoheterotrophs (Pro. Only)
Light for ATP, but needs a Carbon source
Chemoheterotrophs
Consume organic molecules for both energy and carbon source

10. Nutritional Diversity
Saprobes: Decomposers
Parasites: Absord nutrients from living host body fluid
Specificity
Lactobacillus:
Require all 20 a.a.
Several vitamins
E. coli:
Glucose or some other substitute

11. Nitrogen Metabolism Nitrosomes: convert NH4+ to NO2-
Pseudomonas: “Denitrify” NO2- or NO3- to N2 for atmosphere
Cyanobacteria:
use atmospheric nitrogen directly
Nitrogen Fixation: N2  NH4+
Nitrogen – fixing cyanobacteria are most self-sufficient form of life

12. Oxygen and Metabolism Obligate Aerobes Obligate Anaerobes
Use O2 for cellular respiration
Obligate Anaerobes
Poisoned by O2
Live mostly by fermentation
Partly by Anaerobic respiration
Facultative Anaerobes
Use O2 if present
Fermentation if no O2

13. Photosynthesis Evolved Early
Glycolysis was probably among the first metabolic pathways
Photosynthesis likely evolved only once and very early
Cyanobacteria are the only prokaryotic photoautotrophs that release O2 by splitting H2O

14. Archaea Kingdoms Most sorted into Euryarchaeota or Crenarchaeota
Extremophiles
Methanogens (Eury)
CO2 + H2  CH4
Strictest anaerobes live in swamps
Extreme Halophiles (Eury)
Purple-red scum due to bacteriorhodopsin
Extreme Thermophiles (Cren)
Generally °C but up to 105 °C in deep sea vents
Sulfolobus in Yellowstone

15. Bacteria Kingdoms Proteobacteria Alpha Beta Gamma
Closely associated with Eukarya
i.e. Rhizobium, Agrobacterium, Rickettsias, Mitochondria
Beta
Nitrosomonas: NH4+  NO2-
Gamma
i.e. Chromatium, Legionella, Salmonella, Vibrio cholerae, Escherichia coli

16. Bacterial Kingdoms (cont.)
Proteobacteria (cont.)
Delta
Myxobacteria
Secretes a slimy substratum to glide along
When soil is dry it produces “fruiting” bodies
Releases spores to form new colonies
Bdellovibrio
Charges prey at 100 µm/sec
Drills by spinning at 100 rps
Epsilon
Helicobacter pylori: stomach ulcers

17. Bacterial Kingdom (cont. cont.)
Chlamydias
Gram-negative w/o peptidoglycans
Chlamydia trachomatis: causes blindness and nongonococcal urethritis
Spirochetes
Treponema pallidum: Syphilis
Borrelia burgdorferi: Lyme disease

18. Bacteria Kingdoms (will they ever end?)
Gram-Positive Bacteria
Actinomycetes
Tuberculosis and leprosy
Spore formers
Bacillus anthracis
Clostridium botulinum
Staphylococcus and Streptococcus
Mycoplasmas
Smallest of all living cells and lack cell walls
Cyanobacteria: only bacterium with plantlike oxygenic photosynthesis

19. Prokaryotes and Our World
Decomposers: release C, N, and other elements back into the ecosystem
Producers: Provide the base for many food chains
Symbiosis
Mutualistic: Both members benefit
Commensalistic: One member benefits
Parasitic: Parasite benefits while host suffers

20. Human Diseases as a Result of Prokaryotes
Opportunistic
Koch’s Postulate
Find the same pathogen in every diseased individual
Isolate same pathogen and grow microbe in pure culture
Induce disease in experimental animal from culture
Isolate same pathogen from infected animal

21. Toxins Exotoxins: Proteins secreted by pro. Endotoxins Antibiotics
1g of Botulism can kill a million people
Endotoxins
Components of outer membrane of gram-neg. bacteria
Antibiotics
Biological Warfare

22. Human Uses Bioremediation: Mass Production
Organisms are used to remove pollutants from the air, water and soil
Sewage treatment facilities
Mass Production
Insulin production

23. Cyanobacteria

24. Streptomyces and Mycoplasmas

25. Leptospira

26. Chlamydias

27. Helicobacter pylori

28. Myxobacteria and Bdellovibrio

29. Chromatium

30. Rhizobium

31. Photosynthetic Parsimony

32. Gram Stains