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Prokaryotes and Viruses. West Nile Virus. West Nile Virus. One of several mosquito-borne viruses in the United States that can infect people The virus exists in nature primarily through a transmission cycle involving mosquitoes and birds.
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West Nile Virus • One of several mosquito-borne viruses in the United States that can infect people • The virus exists in nature primarily through a transmission cycle involving mosquitoes and birds. • Mosquitoes become infected with West Nile virus (WNV) when they feed on infected birds
West Nile Virus Symptoms • Majority of people that become infected with the West Nile virus have no illness or experience only a mild flu-like illness • May include fever, headache and body aches lasting only a few days • Some persons may also have a mild rash or swollen lymph glands • Less than one percent of those infected may develop meningitis or encephalitis, the most severe forms of the disease
How Long has the West Nile Virus Been Around? • Alexander the Great, 336 B.C., conquered a vast empire • It’s speculated that his demise was due to West Nile encephalitis • There is still no human vaccine for West Nile virus
West Nile Virus Takes Off • West Nile Virus is pathogenic, it invades its host and multiplies, causing disease • It’s a flavivirus, traveling inside mosquitoes which act as the transferring agent from host to host
Impacts, Issues Video West Nile Virus Takes Off
Microorganisms • Single-celled organisms that are too small to be seen without a microscope • Bacteria are the smallest living organisms • Viruses are smaller but are not alive
The Prokaryotes • Only two groups • Archaebacteria and Eubacteria • Arose before the eukaryotes
Prokaryotic Characteristics • No membrane-bound nucleus • Single chromosome • Cell wall (in most species) • Prokaryotic fission • Metabolic diversity
Prokaryotic Body Plan DNA capsule plasma membrane ribosomes in cytoplasm bacterial flagellum pilus cell wall cytoplasm
Prokaryotic Body Plan cytoplasm, with ribosomes DNA, in nucleoid pilus bacterial flagellum outer capsule cell wall plasma membrane
Prokaryotic Body Plan Prokaryotic body plan
Bacterial Shapes coccus bacillus spirillum
Bacterial Shapes sex pilus
Metabolic Diversity • Photoautotrophs • Chemoautotrophs • Chemoheterotrophs
Gram Stain Gram stain
Bacterial Genes • Bacteria have a single chromosome • Circular molecule of DNA • Many bacteria also have plasmids • Self-replicating circle of DNA that has a few genes • Can be passed from one cell to another
Bacterium before DNA replication bacterial chromosome DNA replication begins DNA replication completed parent DNA molecule DNA copy
Membrane growth moves DNA molecules apart New membrane and cell-wall material deposited Cytoplasm divided in two
Prokaryotic Fission - 3 Prokaryotic fission
Conjugation Transfer of plasmid
nicked plasmid conjugation tube
Conjugation Prokaryotic conjugation
EUBACTERIA (Bacteria) ARCHAEBACTERIA (Archaea) EUKARYOTES (Eukarya) Prokaryotic Classification • Traditionally classified by numerical taxonomy • Now increased use of comparative biochemistry
Prokaryotic Classification to ancestors of eukaryotic cells DOMAIN BACTERIA DOMAIN BACTERIA biochemical and molecular origin of life
Eubacteria • Includes most familiar bacteria • Have fatty acids in plasma membrane • Most have cell wall; always includes peptidoglycan • Classification based largely on metabolism
Eubacterial Diversity • Photoautotrophic • Aerobic (Cyanobacteria) • Anaerobic (Green bacteria) • Chemoautotrophic • Important in nitrogen cycle • Chemoheterotrophic • Largest group
Eubacteria Examples of eubacteria
Some Pathogenic Eubacteria • Most are chemoheterotrophs • E. coli strains • Clostridium botulinum • Clostridium tetanus • Borrelia burgdorferi • Rickettsiarickettsii
Some Pathogenic Eubacteria resting spore photo-synthetic cell heterocyst