Classification, Bacteria & Viruses

1. Classification, Bacteria & Viruses AP Biology 2010

2. Systematics • Combination of phylogeny and classification • Classification system: Carl Linnaeus • Domain, kingdom, phylum, class, order, family genus species • Hierarchical; Binomial nomenclature • Genus species

4. Major Lineages of Life 3 domains: Bacteria, Eukaryota, Arachae

5. Prokaryotes: Domains Bacteria & Archae Prokaryotes lack membrane bound organelles (ie. Nucleus, mitochonidria, etc.)

6. Prokaryotic Cell Structure • Almost all have cell walls. Most contain peptidoglycan (exception: members of Archae) • Gram + : simple cell walls with large amounts of peptidoglycan • Gram - : more complex cell walls with less petidoglycan

7. Many have capsules and piliand are motile

8. Prokaryotic Genetic Material & Reproduction • Not in nucleus, concentrated in nucleoid region. • Smaller rings of DNA: plasmids • Reproduce asexually via binary fission • Transformation: can take up genes from surrounding • Conjugation: direct transfer of genes between prokaryotes • Transduction: transfer of genes between prokaryotes via viruses

9. Bacteriaphage: viruses inject DNA into bacterial cells Binary fission

10. Conjugation:

11. Some form endospores: Examples: Clostridium tetani & Clostridium botulinum

12. Nutritional Diversity • Photoautotrophs: photosynthetic • Chemoautotrophs: use carbon dioxide as carbon source but obtain energy by oxidizing inorganic substances like hydrogen sulfide, ammonia, ferrous iron. • Photoheterotrophs: can use light to generate ATP but need carbon in organic form • Chemoheterotroph: must consume organic molecules for energy and carbon

13. Metabolic Relationship with Oxygen • Obligate aerobes • Facultative anaerobes • Obligate anaerobes

14. Archae Extremophiles Thermophiles Halophiles Bacteria Most known bacteria Two prokaryotic domains:

15. Importance of prokaryotes: • Cyanobacteria: evolution of photosynthesis; transformation of atmosphere • Decomposers • Symbiotic: nitrogen fixation • Biotechnology; bioremediation • Pathogens: • Koch’s postulates • Exotoxins

16. What spore-forming bacteria has been in the news in recent years? Lungs – severe pneumonia & death Gastrointestinal – vomiting blood, severe diarrhea Cutaneous – necrotic ulcers

17. Viruses • Can only reproduce within a cell (limited range of host cells) - “hijacks” cell’s nucleic acid and protein synthesis machinery • Protein shell – capsids and some have viral envelopes

18. Different capsid structures and viral envelope proteins

19. Bacteriaphage

20. Lytic life cycle Lysogeneic Life cycle

21. Host Range • Glycoproteins in viral envelope bind to a cell surface receptor protein on host cell and gains entry into the cell. Example: HIV binds to CD4 receptors of T immune cells

23. Classes of Viruses • DNA viruses • Retroviruses – RNA (HIV) RNA Reverse transcriptase makes DNA DNA integrates into cell’s genome (provirus)

24. List of Viruses • HIV • Ebola • Influenza • SARS • Dengue • Hantavirus • Hepatitis • West Nile • Marburg • Lassa • Human monkeypox You will be assigned a virus – make a powerpoint slide about your virus. Include type of virus, method of transmission, incubation, symptoms, treatment, prevention and any other interesting facts

25. Prevention/Treatment • Vaccines: influenza, polio, measles, mumps, rubella, hepatitis, chicken measles, etc. • Problems with development of HIV vaccine: dead virus does not retain antigenicity, too dangerous to use live attenuated virus. Also highly mutable envelope proteins • Ongoing research with SIV in chimps