PowerLecture: Chapter 21 Prokaryotes and Viruses

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

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

Bacterial Shapes coccus bacillus spirillum p. 334

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

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

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

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

Metabolic Diversity Photoautotrophs Photoheterotrophs Chemoautotrophs Chemoheterotrophs

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Magnetotactic Bacterium Fig. 21-9, p.339

Archaebacteria Fig. 21-10, p.340

Archaebacteria Methanogens Extreme halophiles Extreme thermophiles

` Methanogens Fig. 21-11b, p.340

Extreme Halophiles Fig. 21-12a, p.341

Extreme Thermophiles Fig. 21-12b, p.341

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

Viral Body Plans DNA or RNA Protein Coat Complex virus (bacteriophage) Helical virus Polyhedral virus Fig. 21-13, p.342

Enveloped Virus (HIV) viral protein lipid envelope (derived from host) viral RNA reverse transcriptase viral coat (proteins) Fig. 21-13, p.342

Virus viral RNA protein subunits of coat 18 nm diameter, 250 nm length Fig. 21-13a, p.342

Virus 80 nm diameter Fig. 21-13b, p.342

Bacteriophage 65–nm diameter head, 225 nm total length DNA protein coat sheath base plate tail fiber Fig. 21-13c, p.342

Enveloped Virus (HIV) viral coat (proteins) reverse transcriptase 100-120 nm diameter viral RNA lipid envelope: proteins span the envelope, line its inner surface, spike out above it Fig. 21-13d, p.342

Viruses Fig. 21-14a, p.343

Viruses Fig. 21-14b, p.343

Viruses Fig. 21-14c, p.343

Viruses Fig. 21-14d, p.343

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

Lytic Pathway Fig. 21-15a, p.344

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. 21.20 Page 358

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 21.20 (2) Page 358

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 21.16 Page 345

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

Mycobacterium tuberculosis p.346a

SARS virus p.346b

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

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

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

Fig. 21-17a, p.347

Fig. 21-17b, p.347

Fig. 21-17c, p.347

Fig. 21-18a p.349

Fig. 21-18b p.349

Fig. 21-18c p.349