1. THE PROKARYOTES

2. Systematics Focus on animals and plants How to classify prokaryotes?
History limited to 20% of evolutionary time
How to classify
prokaryotes?
Limited in
morphological
characters

3. Carl Richard Woese
, USA; Developed system based on 16S rRNA in 1977

4. Carl Woese and George Fox

5. rRNA
Emile Zuckerkandl ( ); Austria & USA. Molecular biology and molecular clock
Linus Carl Pauling ( ) USA Founder of fields like quantum chemistry and molecular biology
Suggested that a tree of life might be generated by comparing sequences of biopolymers like RNA
Zuckerkandl and Pauling

6. Flow of information in a cell…

7. When DNA is transcribed, the result is an RNA molecule
DNA molecule
Gene 1
Gene 2
Gene 3
DNA strand
Transcription
RNA
Translation
Codon
Polypeptide
Amino acid
Figure 10.10

8. When DNA is transcribed, the result is an RNA molecule
RNA is then translated into a sequence of amino acids
DNA molecule
Gene 1
Gene 2
Gene 3
DNA strand
Transcription
RNA
Translation
Codon
Polypeptide
Amino acid
Figure 10.10

9. A typical prokaryotic cell
Ribosomal Function
A typical prokaryotic cell
may have
10,000+ ribosomes

10. Where does rRNA enter the picture?

11. Ribosomal Structure
Two subunits

12. Ribosomal subunits= rRNA molecules + proteins

13. Prokaryotes Eukaryotes

14. What’s the ‘S’?
Svedberg units: a measure of how quickly particles sediment in an ultracentrifuge

15. What’s the ‘S’?
Svedberg units: a measure of how quickly particles sediment in an ultracentrifuge
Larger the particle, the greater its S value
Smaller subunit of a ribosome sinks slower than the larger subunit

16. Why then does 5S + 23S = 50S?

17. Why then does 5S + 23S = 50S? Shape AND size determine sedimentation rate…

18. Ribosomal RNA Molecules
Components of the ribosomes of ALL ORGANISMS
Changes in nucleotide sequence indicative of evolutionary history
“highly conserved molecules”…
What does this mean?

19. Ribosomal Function PROTEIN SYNTHESIS Not much room for error!
Disruption of ribosome structure likely to disrupt protein synthesis…
Life threatening!

20. Practical applications…
Some antibiotics (e.g. erythromycin and streptomycin) work by targeting the 70S ribosomes
Alter shape and prevent bacteria from synthesizing proteins needed to survive
Why are our own ribosomes not affected by the same drugs???

21. A modification of Woese from Brock et al. (1994).

22. Two different supertrees generated by ML methods for complete genomes of 45 taxa. Daubin et al. 2002

23. Ciniglia et al. 2004

24. Lang et al. 2013
Using 24 genes and 3000 taxa

25. Gram Stain and Structure

26. Eubacteria >9 Kingdoms Same type of ribosomes
Polysaccharide of outer wall made of murein
Most groups involved in global nutrient cycling
Many of economic importance
Disease
Other functions (e.g. antibiotic producers)

27. Proteobacteria
Disparate functional groups joined by molecular sequences
Likely the source of mitochondria

28. Alphaproteobacteria Rikettsias (typhus Rocky Mtn spotted fever
Rhizobias (N-fixing bacteria)
Likely the ancestor of mitochondria was from this group

29. Gammaproteobacteria Usually small rods or cocci
Causative agents of Bubonic Plague, Tuleremia, Legioner’s Disease, Cholera
Includes Escherichia coli

30. Spirochaetae

31. Spirochaetae Spiraled with internal flagella Many are free-living
Causative agents of Lyme disease, syphilis, yaws, and relapsing fever

32. Cyanobacteria

33. Cyanobacteria Like free-living chloroplast
Group from which chloroplasts appeared
Form filaments, colonies
Very large for bacteria
Some produce toxins
Many are nuisance algae in over-fertilized waters
Source of most atmospheric oxygen, especially prior to eukaryotes

34. Firmicutae
Lack second outer membrane of Eubacteria
Gram positive

35. Aphragmabacteria Tiny, smallest genome of any non-virus No walls
Obligate parasites
One causes pneumonia; many plant pathogens

36. Anoxybacteria Obligate anaerobes
Causative agents of botulism and tetanus
Botox
Common in soil and animal digestive systems

37. Endosporobacteria Produce resistant spores
Many major human pathogens, including anthrax, staph (including methicillin-resistant Staphylococcus aureus), strep
Includes Lactobacillus

38. Actinobacteria Many are slow-growing and fungus-like
Antibiotic sources (e.g. streptomycin, actinomycin)
Causative agents of leprosy and tuberculosis; diptheria
Bacteria which cause holes in Swiss cheese
Bifida, a necessary commensal in our lower bowel

39. Deinococcobacteria Thermophiles
Deinococcus withstands 6,000 rads (and up to 1500 megarads)
Thermus, found at Yellowstone, enzymes used for PCR

40. Archaea Differ from the Eubacteria Form of ribosomes No murein
Different lipids
Different RNA polymerase

41. Crenarchaea These are the hyperthermophiles
They tend to inhabit very hot environments that are rich in sulfur

42. Euryarchaeota
Halobacteria
Methanobacteria
Thermoplasmobacteria

43. Viruses Non-cellular Usually nucleic acid and protein Types
DNA (ss & ds)
RNA (ss & ds)
DNA RT
RNA RT
Prions

45. Some Human Viral Diseases
Herpes
Smallpox
Hepatitis (B, C, D)
Yellow Fever
Dengue fever
West Nile
HIV
Ebola
Rabies
Chicken Pox /Shingles
Rubella (German Measles)
Influenza
Polio
Mumps
Measles
Epstein-Barr
Hemorrhagic fever
Rota
Rhinovirus
Transmissible spongiform encephalopathy (TSE)

46. Theories on Origin of Viruses
Regressive Hypothesis: cellular parasites of larger cells that became simplified
Cellular Origin Hypothesis: pieces of living cells that can replicate (e.g. strands of nucleic acids like plasmids or transposons)
Coevolution Hypothesis: evolved together with the first cells as their parasites