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Viruses

Viruses. Chapter 24. Standards. Standard 1: Cells CLE 3216.1.6 Describe the relationship between bacteria, protists, and viruses and their host cells Prokaryotes. Viruses. NOT living (don ’ t meet all requirements) Ex: Don ’ t grow and develop Needs a host to survive

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Viruses

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  1. Viruses Chapter 24

  2. Standards • Standard 1: Cells • CLE 3216.1.6 • Describe the relationship between bacteria, protists, and viruses and their host cells • Prokaryotes

  3. Viruses • NOT living (don’t meet all requirements) • Ex: Don’t grow and develop • Needs a host to survive • Cannot carry out cellular functions • Core of DNA or RNA surrounded by protein coat • Reproduce only by infecting living cells

  4. Viral Diseases • Viruses that cause disease attack and destroy cells • Cannot be treated with antibiotics (maybe over the counter medicines) • Vaccines work if used before virus is contracted

  5. Common Viral Diseases • Common cold • Flu • AIDS • Chicken Pox/Shingles • Hepatitis B • West Nile Virus

  6. Virus Structure • Core filled with genetic material inside • Capsid =protein coat • Proteins attach to cell “tricking” it into letting the virus in • Viral genes are copied • Host cell dies • Bacterophage = virus that only infects bacteria

  7. Classification of Viruses • Have RNA vs DNA as their genome • Double stranded vs Single stranded • Linear vs Circular

  8. Viral Infection • 2 viral infection processes: • Lytic infection - host cell bursts • Lysogenic infection - virus remains inactive inside of host for periods of time

  9. Lytic Infection • Virus DNA is injected into host cell • Cell begins to copy virus DNA, then make virus proteins • Virus proteins break down host cell and uses it to copy more viruses • Cell finally bursts (lyses)

  10. Lysogenic Infection • Virus DNA is injected into host cell’s DNA • DNA is replicated with included viral DNA • Cell does not lyse - virus remains inactive for period of time • Then enters lytic cycle when inactivation is over

  11. Retrovirus • Virus with RNA as genetic material • Retro = backwards • Copies RNA into DNA instead of DNA to RNA • Ex: AIDS

  12. Emerging Disease • Illness caused by new or reappearing agents that typically exist in animal populations • Ex: Ebolo virus

  13. Viroids and Prions • Viroids: smallest known particles known to replicate - Infect plants • Prions: Infectious protein particles - causes degenerative brain diseases Ex: Mad cow disease

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