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Virus!. Not Alive, But Still Deadly…. Bacteriophages or Virus?. Bacteriophages or Virus?. Bacteriophages attack bacteria (prokaryotes) viruses attack eukaryotic cells (animal and plant cells).
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Virus! Not Alive, But Still Deadly…
Bacteriophages or Virus? • Bacteriophages attack bacteria (prokaryotes) • viruses attack eukaryotic cells (animal and plant cells). • Viruses and bacteriophages take over cells and use the host cell's organelles to make more of their own parts.
Viral Size and Structure • Virus shape is determined by the DNA/RNA and protein coat covering its genome (DNA/RNA) • Basic structure: • Capsid: Protein coat • Nucleic acid core: RNA or DNA • Genome can be single or double stranded • Helps determine shape of virus • Lipoprotein coat • Envelopes (covers) capsid in some viruses
Virus Categories • DNA viruses – stable, do not mutate rapidly • Single-stranded or double-stranded • Includes Smallpox and Hepatitis B • RNA viruses – mutate rapidly, unstable • Single-stranded or double-stranded • Includes HIV and Rhinovirus
The Lytic Cycle • Virus attaches to host cell’s membrane and injects its nucleic acid into the host cell. • The viral nucleic acid takes over protein synthesis, creating new viruses. • The host cell bursts, lyses, releasing the newly formed viruses.
The Lysogenic Cycle • Nucleic acid of virus becomes part of the host cell’s chromosome • Nucleic acid remains in the cell in this form for many generations
HIV and AIDS • HIV is a retrovirus that leads to AIDS • The virus kills or damages cells of the body's immune system, progressively destroying the body's ability to fight infections • 25 million people worldwide have died from AIDS • A combination of at least three drugs is recommended to suppress the virus from replicating and boost the immune system • There is no cure for HIV and AIDS
Chickenpox • Caused by the varicella-zoster virus (VZV) and common in children under 12 • Highly contagious, itch rash • Children can be vaccinated against the disease • Some children may still get chickenpox though • Those that have had chickenpox have a natural immunity to the disease • VZV can lie dormant within the body and cause shingles later in life
Influenza • Two common types: Influenza A and Influenza B • Flu Symptoms include: • fever (usually high), headache, extreme tiredness, dry cough, sore throat, runny/stuffy nose, muscle aches • Nausea, vomiting, and diarrhea can occur but are more common in children • 5% to 20% of U.S. residents will get influenza each year • 36000 people on average die from influenza-related causes • 200,000+ will admitted to the hospital as a result of influenza-related causes.
Smallpox and Vaccination • Edward Jenner is credited with the first vaccination against smallpox • Country-lore suggested that people who caught cowpox from their cows did not get smallpox • Jenner transferred material from the pocks of a dairymaid to James Phipps, the 8 year old son of his gardener • James became mildly ill from cowpow • Weeks later, Jenner infected James with smallpox • No infection now or during future trials • The first vaccination published was a success!