1. PowerLecture: Chapter 21
Prokaryotes and Viruses

2. Prokaryotic Characteristics
(Archaebacteria and Eubacteria )
No nucleus
1 circular molecule of DNA
(many also have plasmids)
Cell wall (in most)
Prokaryotic fission
Metabolically diverse

3. cytoplasm, with ribosomes
Prokaryotic Body Plan
cytoplasm, with ribosomes
DNA, in nucleoid
pilus
bacterial flagellum
outer capsule
cell wall
plasma
membrane
Fig. 21-2, p.334

4. Bacterial Shapes
coccus
bacillus
spirillum
p. 334

5. Bacterial Shapes
Fig. 21-3a, p.335

6. Bacterial Shapes
Fig. 21-3b, p.335

7. Bacterial Shapes
Fig. 21-3c, p.335

8. Bacterial Shapes
sex pilus
Fig. 21-3d, p.335

9. Metabolic Diversity Photoautotrophs Photoheterotrophs Chemoautotrophs
Chemoheterotrophs

10. Gram Stain Separates bacteria into 2 groups based on how cell wall stains
Fig. 21-4, p.335

11. Prokaryotic Fission
Fig. 21-5g, p.335

12. DNA replication begins DNA replication completed
Bacterium before
DNA replication
bacterial chromosome
DNA replication begins
parent DNA molecule
DNA copy
DNA replication completed
Stepped Art
Fig. 21-5a-c, p.336

13. Membrane growth moves DNA molecules apart
New membrane and cell-wall material deposited
Cytoplasm divided in two
Stepped Art
Fig. 21-5d-f, p.336

14. Conjugation
Transfer of plasmid
Fig. 21-6, p.337

15. nicked plasmid
conjugation tube
Stepped Art
Fig. 21-6, p.337

16. Prokaryotic Classification
EUBACTERIA
(Bacteria)
ARCHAEBACTERIA
(Archaea)
EUKARYOTES
(Eukarya)

17. Prokaryotic Classification
to ancestors of eukaryotic cells
DOMAIN BACTERIA
DOMAIN ARCHAE
biochemical and molecular origin of life
p.337

18. Eubacteria Most familiar bacteria fatty acids in plasma membrane
Cell wall always includes peptidoglycan
Classified based on metabolism

19. Eubacterial Diversity
Photoautotrophic
Aerobic (Cyanobacteria)
Anaerobic (Green bacteria)
Chemoautotrophic
Chemoheterotrophic
Largest group

20. Eubacterial Diversity
Fig. 21-7a, p.338

21. Some Pathogenic Eubacteria
Most are chemoheterotrophs
Examples (you don’t need to write these)
E. coli strains
Clostridium botulinum
Clostridium tetanus
Borrelia burgdorferi
Rickettsia rickettsii

22. Cyanobacteria example-Anabaena
resting spore
photo-synthetic cell
heterocyst
Fig. 21-8a, p.339

23. Some Pathogenic Eubacteria Clostridium tetani
DNA
spore coat
capsule around cell wall
Fig. 21-8d, p.339

24. Bacterial Behavior move toward what they need..
Examples (you don’t need to write these)
Aerobes move toward oxygen; anaerobes avoid it
Photosynthetic types move toward light
Magnetotactic bacteria swim downward

25. Magnetotactic Bacterium
Fig. 21-9, p.339

26. Archaebacteria
Fig , p.340

27. Archaebacteria
Methanogens
Extreme halophiles
Extreme thermophiles

28. `
Methanogens
Fig b, p.340

29. Extreme Halophiles
Fig a, p.341

30. Extreme Thermophiles
Fig b, p.341

31. Virus Noncellular Protein around nucleic acid core
Cannot reproduce self… produced by host cell

32. Viral Body Plans DNA or RNA Protein Coat Complex virus (bacteriophage)
Helical virus
Polyhedral virus
Fig , p.342

33. Enveloped Virus (HIV) viral protein lipid envelope (derived from host)
viral RNA
reverse transcriptase
viral coat (proteins)
Fig , p.342

34. Virus viral RNA protein subunits of coat 18 nm diameter, 250 nm length
Fig a, p.342

35. Virus
80 nm diameter
Fig b, p.342

36. Bacteriophage 65–nm diameter head, 225 nm total length DNA
protein coat
sheath
base plate
tail fiber
Fig c, p.342

37. Enveloped Virus (HIV) viral coat (proteins) reverse transcriptase
nm diameter
viral RNA
lipid envelope: proteins span the envelope, line its inner surface, spike out above it
Fig d, p.342

38. Viruses
Fig a, p.343

39. Viruses
Fig b, p.343

40. Viruses
Fig c, p.343

41. Viruses
Fig d, p.343

42. Viral Multiplication - Basic Steps
Attach to host cell
Virus or Nucleic acid enters host
Host incorporates viral Nucleic acid
Host uses viral info to assemble new viral particles
Release new viral particles

43. Lytic Pathway
Fig a, p.344

44. Lysis of host cell is induced; infectious particles escape.
Lytic Pathway
Tail fibers and other parts are added to coats.
Virus particles bind to wall of suitable host. Viral genetic material enters cell cytoplasm.
Viral protein molecules are assembled into coats; DNA is packaged inside.
Viral DNA directs host machinery to produce viral proteins and viral DNA.
Stepped Art Fig Page 358

45. Viral DNA usually becomes integrated into the bacterial chromosome.
Lysogenic Pathway
Viral DNA is excised from chromosome and cell enters lytic pathway.
Prior to prokaryotic fission, the chromosome and integrated viral DNA are replicated.
After binary fission, each daughter cell will have recombinant DNA.
Stepped Art Fig (2) Page 358

46. Replication of an Enveloped Virus
DNA virus particle
plasma membrane
of host cell
Transcription
of viral DNA
Replication
of viral DNA
Translation
nuclear
envelope
some proteins for viral coat
viral DNA
other proteins
for viral envelope
Figure Page 345

47. Evolution and Disease Host and pathogen coevolving
pathogen kills too quickly, it might disappear along with the host
Most dangerous if pathogen is…
overwhelming in numbers
in a novel host
a mutant strain

48. Mycobacterium tuberculosis
p.346a

49. SARS virus
p.346b

51. New Threats Emerging Pathogens Drug-resistant strains Food poisoning
Ebola virus
Monkeypox virus
SARS virus
Drug-resistant strains
Food poisoning
E. coli
Salmonella

52. Viroids Smaller than viruses Strands or circles of RNA
No protein-coding genes
No protein coat
Cause many plant diseases

53. Prions Small proteins Linked to human diseases Animal diseases
Creutzfeldt-Jakob disease (CJD)
Kuru
Animal diseases
Bovine spongiform encephalopathy (mad cow disease)
Scrapie in sheep

54. Fig a, p.347

55. Fig b, p.347

56. Fig c, p.347

57. Fig a
p.349

58. Fig b
p.349

59. Fig c
p.349