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Warm Up

This lesson covers essential aspects of viruses, including their structure, replication processes, and the impact they have on human health. Students will learn the major components of viruses, differentiating between lytic and lysogenic cycles, and the necessity of host cells for viral replication. A focus will also be placed on real-world examples of viral infections that have harmed humanity, alongside preventive measures like vaccinations. Engaging activities will be provided to enhance understanding and retention of the material.

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Warm Up

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Presentation Transcript

  1. Warm Up • Monday, March 18, 2013 • Which process copies a strand of DNA (DNA to DNA)?

  2. Virus Notes

  3. Objectives • List the major components of a virus. 2) List the steps involved in virus replication. 3) Describe a real world scenario in which viruses have had a negative impact on human lives.

  4. Viruses • NOT living organisms • Infects host cells • Inject their genetic material into host • Needs host in order to replicate

  5. Parasites = depend entirely upon another living organism to survive, harming organism in process • Viruses = parasites • Take advantage of hosts respiration, nutrition, & all other functions

  6. Virus Genetics • Composed of DNA or RNA core • Surrounded by protein coat • Simplest: few genes • Most complex: >100 genes

  7. Capsid = Protein coat that surrounds DNA/RNA • Enable virus to enter host cell • Bind to receptors on surface of cell • “Trick” cell into letting it in • Once inside, viral genes expressed

  8. Cold Viruses

  9. Flu Virus

  10. Viruses Specific • Bind to specific proteins on host cell’s surface • Why does it matter? • Infect specific cells • Infect specific organisms • Example: • HIV infects humans • Parvovirus infects dogs, wolves, & foxes

  11. Bacteriophage = virus that infects a bacterial cell • Structure: • Head = contains DNA • Neck • Collar • Sheath • Tail Fiber • Base Plate

  12. Lytic Infection • Virus enters cell • Virus copies itself • Cell bursts

  13. Lytic Cycle • 5 Stages: • Attachment (a) - virus attaches itself to host cell • Injection (a & b) - virus inserts its genetic material into host cell • Integration (c) - genetic material tells the cell what to do • Replication (d) - host cell builds parts of virus  Assembly (d) - cell assembles replicated parts into progeny viruses  5) Lysis (e)- cell breaks open & ea. replicated virus can  infect other cells

  14. Lysogenic Cycle • Latent period extends cycle • Viral DNA becomes part of host chromosome for a time

  15. Lysogenic Infection • Virus enters (a-1) • Integration: Virus integrates viral DNA w/ host cell DNA (a-2) • Viral DNA is replicated (when host cell replicates DNA) (a-3) • Host cell completes mitosis & makes other cells infected w/ virus(a-4) ***Difference: Host cell does NOT burst!!! (b)***

  16. Prophage • Viral DNA that’s embedded in the host’s chromosome (DNA)

  17. Retrovirus = contain RNA as the hereditary material in place of the more common DNA • Genetic information copied backward • RNA to DNA (usually other way) • May remain dormant & wait for right conditions to become active • Dormant = not active (like sleeping)

  18. Retrovirus • Example: • virus that causes AIDS • (acquired immune deficiency syndrome)

  19. Viral Diseases • CanNOT be treated w/ antibiotices • Must PREVENT infection • Vaccinations • Stopping spread

  20. Other Viral Diseases • Chicken Pox • Symptoms: fever and weakness, red, itchy rash • Spread By: contact w/ rash • Prevention: Vaccine

  21. Other Viral Diseases • Measles • Symptoms: High fever, sore throat, cough, rash, sneezing, swollen eyelids, whiter spots on cheek lining • Spread By: Droplet inhalation • Prevention: Vaccine

  22. Other Viral Diseases • West Nile • Symptoms: Fever, headache, body ache- • Spread By: Bite from an infected mosquito • Prevention: Mosquito repellant, avoid going outside at dawn & dusk, avoid standing water

  23. AVID Thinking Strategies • WANTED Virus Poster (2 colors) • Include: • The words “WANTED” at the top • Virus name • Drawing of virus or picture that depicts aspect of virus life cycle (Ex: mosquito for west nile) • Symptoms that are seen in infected host • How virus spread • Prevention/Treatment

  24. Warm Up • Tuesday, March 19, 2013 • Which process creates a strand of RNA (DNA to RNA)?

  25. Germ Warfare Reading & Summaries

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