1 / 17

Advanced Biology Chapter 27

Advanced Biology Chapter 27. Viruses. Nature of Viruses. Viral Basic Structure: DNA or RNA Protein Coat It is not living It is not a cell and has no cellular structures other than having nucleic acid. Viruses vary in shape and Size. More shapes and Sizes. Viruses invade cells.

conor
Download Presentation

Advanced Biology Chapter 27

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. Advanced BiologyChapter 27 Viruses

  2. Nature of Viruses • Viral Basic Structure: • DNA or RNA • Protein Coat • It is not living • It is not a cell and has no cellular structures other than having nucleic acid

  3. Viruses vary in shape and Size

  4. More shapes and Sizes

  5. Viruses invade cells • Viruses cannot replicate on their own, they need a host • Their host vary from bacteria, protists, plants and animals (including humans) • They are usually host specific (host range) and sometimes tissue specific (tissue tropism) • Viruses can remain dormant in cells for years (chicken pox and shingles caused by varicella zostervirus) • Viruses invade the host cell and use the cells protein synthesis processes to make viral proteins and take over the cell

  6. Lytic vs. Lysogenic Cycle • Lytic - When a virus kills an infected host cell by rupturing the cell • Lysogenic - When a virus enters the cell and integrate themselves into the nucleic acids of the host cells. This allows them to be replicated along with the DNA

  7. http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter17/animation_quiz_2.htmhttp://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter17/animation_quiz_2.htm

  8. HIV • AIDS (Auto Immune Deficiency Syndrome) is caused by Human Immunodeficiency Virus • Thought that HIV might be related to smallpox virus • HIV targets CD4+ cells such as T-helper cells which aids in the immune response system. • HIV is a retrovirus thus it has RNA instead of DNA • HIV enters the cells and goes through reverse transcriptase (DNA made from RNA). • HIV then makes another copy of DNA and incorporates itself into the DNA of the host • This allows them to use hosts protein synthesis to make more viral proteins and more HIV particles.

  9. Other Viral Diseases • See page 532, Table 27.1 • Three basic types of flu: • Type A (causes most serious flu epidemics in humans but can infect other mammals and birds) • Type B (humans only) • Type C (humans only) • Subtypes are based on their protein spikes emerging from their capsid

  10. Various Flu Epidemics • Called the H1N1 killed 20-50 million people • Asian Flu of 1957 (H2N2) over 100,000 Americans • Hong Kong Flu of 1968 (H3N2) 70,000 Americans • Flues are different strains that change/evolve constantly and can sometimes change over from a virus in one species to another (birds to humans)

  11. Emerging Viruses • Any virus that can transfer from one species to the next is considered an emerging virus • Some of these include: • Hantavirus – Deer mouse to humans (pneumonia 1993) • Hemorrhagic fever (filovirus) –causes hemorrhagic fever and death rates over 50% • Ebola virus is one of the worst with 90% death rates in Africa (unknown source) • Summer of 1995 – Zaire – killed 245 out of 316 infected

  12. Ebola Virus

  13. SARS • SARS (Severe acute respiratory syndrome) • Respiratory infection • Acts like pneumonia • 8% fatality rate • Outbreak in 2003 • Unknown source • Maybe civets (weasel-like) in China • Or bats • Vaccines are becoming available

  14. Cancer • Some viruses can cause cancer • Hepatitis B and liver cancer connection • Human Papillomavirus (HPV) and cervical cancer

  15. Prions • Prions are proteins that cause disease (proteinaceous infectious particle) – Stanley Prusiner – 1970 • Prions can cause diseases such as TSE (transmissible spongiform encephalopathies) • In this case, neurons die out and an empty space makes the brain look like a sponge. • Mad Cow Disease • Chronic Wasting Disease • Creutzfeldt-Jakob Disease

  16. Viroids • Viroids are small RNA molecules that are circular and they do not have a protein coat. • Viroids somehow replicate without any helper cells • They only infect plants • 10 million coconut palms killed in Philippines • Relatively new infectious agent that is still being studied

More Related