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Bacteria & Viruses. Bacteria – Structure. Prokaryotic single cells Shapes Sphere (cocci), Rod (bacilli), or Spiral (spirilli) Organization Often clusters (staphylo-) or chains (strepto-). Shapes of Bacteria. UNDERSTANDING CHECK. Staphylococcus epidermidis. MRSA. Streptococcus pyogenes.
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Bacteria – Structure • Prokaryotic single cells • Shapes • Sphere (cocci), Rod (bacilli), or Spiral (spirilli) • Organization • Often clusters (staphylo-) or chains (strepto-)
Bacteria - Structure • Eubacteria have cell walls • Gram negative have 2nd cell wall • Gram positive do not • Negative = no antibiotics • Movement • Many have flagella
Bacterial Reproduction • Binary Fission – happens QUICKLY!
Bacteria -Variations • Obligate anaerobes • Clostridium botulinum • Facultative anaerobes/aerobes • E. coli • Obligate aerobes • Tuberculosis
Bacteria – Obtaining Nutrients • Autotrophic • Photosynthetic (Cyanobacteria) • Chemosynthetic (Methanogens) • Heterotrophic • Parasitic (Tuberculosis) • Decomposers
Uses of Bacteria • Beneficial • Decomposers • Manufacture of food – yogurt, cheese, pickles • Pathogens – disease-causing • Food poisoning
What causes diseases? • Francesco Redi – Spontaneous Generation - 1665
Transmission of Diseases • Airborne • Water • Direct contact • Vectors - transmitters of disease that carry the pathogens from one host to another
Treating Bacterial Diseases • Antibiotics • 1928 Fleming – penicillin mold toxic to bacteria • Antibiotic Resistance • Not all bacteria die from antibiotics • People don’t finish prescription • Over-prescribed
VIRUSES • NONLIVING pathogens • Do not metabolize, grow, or maintain homeostasis • Structure – RNA or DNA with protein capsid
How do viruses cause disease? • Rely on living cells (hosts) for replication • Insertion of either the entire virus or just the DNA into the host cell
How do viruses cause disease? • Some viruses turn the cell into a virus making factory, bursting the cell with new viruses • Other viruses replicate slowly and can lay dormant before take-over
Example of viral take-over • CLICK!
Treating Viral Diseases • Vaccines – inject dead or weak virus so the body can form antibodies • Edward Jenner – 1800s - smallpox • Anti-viral drugs – try to disable replication in some way