1 / 30

Viruses

Viruses. What is a virus?. Microscopic disease causing agent Nucleic Acid (DNA or RNA) with a Protein Coat. What is a virus?. Microscopic disease causing agent Nucleic Acid (DNA or RNA) with a Protein Coat ( capsid ). What do viruses require in order to reproduce?. A host cell! .

lucky
Download Presentation

Viruses

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Viruses

  2. What is a virus? • Microscopic disease causing agent • Nucleic Acid (DNA or RNA) with a Protein Coat

  3. What is a virus? • Microscopic disease causing agent • Nucleic Acid (DNA or RNA) with a Protein Coat (capsid)

  4. What do viruses require in order to reproduce? • A host cell!

  5. What are prokaryotic viruses called? • Bacteriophage • There are 10^31 different bacteriophages! (more than all of the stars in the universe)

  6. What are the two ways in which phages infect bacterial cells? Virulent Phage - Lytic Cycle: -Infection, Synthesis, Assembly, Release

  7. What are the two ways in which phages infect bacterial cells? • Temperate Phage – Lysogenic Cycle

  8. Lysogenic Cycle • Phage DNA splices into bacterial chromosome • When cell replicates, phage DNA is replicated • May enter lytic cycle • Ex: Lambda Phage

  9. Lytic versus Lysogenic Cycle

  10. Eukaryotic Viruses are much more diverse than prokaryotic viruses… • DNA or RNA genomes (single OR double stranded) • B. Lipid Envelope that surrounds the protein coat

  11. Influenza Virus • RNA Virus • Responsible for more deaths in human history than any other known virus • Easily transmitted in aerosol form

  12. Influenza Virus • Binds to receptor on cell surface • Viral RNA is transcribed And translated using host Cell machinery • New viruses assemble And get released from cell

  13. Influenza Virus • Mutates rapidly, so permanent immunity is not possible -> rapidly evolve and acquire new phenotypes • RNA viruses lack replication error mechanisms and can combine/recombine with related viruses IF they infect the same host cell

  14. Influenza Evolution

  15. HIV: Human Immunodeficiency Virus • Retrovirus • RNA genome • Virus contains a code for the enzyme “reverse transcriptase”

  16. HIV • Reverse Transcriptase makes a DNA copy of its genome, which is then splices into the host cell chromosome • RNA -> DNA = Central Dogma VIOLATION!!

  17. HIV • Acute infection is similar to flu symptoms • Virus targets CD4 T-Helper Cells • As the virus destroys the immune system, the body becomes prone to “opportunistic infections”

  18. HIV • Can only be spread through bodily fluid exchange • Many treatments available to slow the progression of the virus • High mutation rates of HIV make it difficult to find one treatment/vaccine

  19. Do plants acquire viral infections? • YES! • Typically manifest as “blotchy” pigment patterns

  20. Viroids are even smaller than Viruses… • Disease causing RNA molecules in plants • Do NOT code for proteins • Interfere with regulation of plant growth

  21. Prions are infectious protein molecules • Disease causing protein molecules • Have no genetic material • Capable of transforming the normal prion protein into mutated/infectious proteins causing tissue damage and death • Mad Cow Disease, Scrapie (sheep)

  22. How do bacteria transmit DNA? • Transformation • Transduction • Conjugation • Transposition • These are all mechanisms to help increase genetic variation in bacteria!

  23. Transformation • Uptake of naked DNA from the environment • Can be a Plasmid or DNA fragment

  24. Transduction • Viral transmission of bacterial DNA

  25. Conjugation • Direct cell-to-cell transfer of genetic material

  26. Transposition • Movement of DNA segments within and between DNA molecules

More Related