1 / 20

Viruses

Viruses. Homework. Cell Analogy Project due Monday 10/5. Objectives. Know the two major differences between a virus and a cell Know how a virus replicates itself. Viruses. How many viruses can the class name off the tops of our heads?. Viruses.

mark-price
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. Homework • Cell Analogy Project due Monday 10/5

  3. Objectives • Know the two major differences between a virus and a cell • Know how a virus replicates itself

  4. Viruses • How many viruses can the class name off the tops of our heads?

  5. Viruses • How many viruses can the class name off the tops of our heads? • HIV, influenza, H1N1, rhinovirus, herpes, HPV, smallpox, polio, chickenpox, ebola, hanta, avian influenza, SARS, hepatitis, norovirus, dengue, Epstein-Barr, marburg, filoviruses • Major viruses you probably haven’t heard of include viruses infecting other animals (SIV, foot and mouth), many plant viruses (tobacco mosaic virus), bacteria viruses like T4 phage

  6. Viruses • Is a virus another kind of bacteria? • How do they cause damage to the infected organism?

  7. Definition • Virus = a microscopic infectious agent that replicates but is not truly alive* *By most scientists’ reckoning

  8. Viruses • Viruses are not cells. • They have only two real parts, and only one of them can also be found in cells.

  9. Viruses • They consist of a protein capsid (envelope or shell) that contains genetic material. • Often this genetic material is DNA, like a cell. Sometimes it’s closely-related RNA instead, in what are called retroviruses.

  10. Viruses • This means cells have what parts that viruses don’t? • What does this mean that viruses cannot do for themselves?

  11. Viruses • A virus can do one thing and one thing only: they force a cell (a host) to make more copies of the virus.

  12. Viral Replication • http://videos.howstuffworks.com/hsw/8061-viruses-how-viruses-work-video.htm • http://www.hhmi.org/biointeractive/media/viral_lifecycle-lg.mov • http://student.ccbcmd.edu/courses/bio141/lecguide/unit3/viruses/adlyt.html • In spite of this, it’s not usually lysing cells that cause pain and symptoms, but it’s actually the body’s defense mechanisms that cause discomfort.

  13. Checkpoint • How is a virus different from a cell? • How is viral replication different from how a cell can reproduce?

  14. Viruses in History • Smallpox and the destruction of Native American civilizations • Mexico’s population: 18 million to 1.6 million in 100 years • American & Canadian Nations reduced to 5% of former population (20 million) in 200 years • Smallpox eradication in 20th century

  15. Viruses in History • Influenza Pandemic of 1918 • http://videos.howstuffworks.com/hsw/8063-viruses-the-influenza-pandemic-of-1918-video.htm

  16. Viruses in History • HIV pandemic • HIV mutated from SIV • The more closely related two species are, the easier it is for them to share viral illnesses • Discovered in the 1980s, 25 million dead since 1981 • 1/3 in Subsaharan Africa, ~6% children • Fast mutating, no cure or vaccine yet. • Clearly understood transmission & pathology • Many treatments & application of evolutionary principles mean it’s no longer “a death sentence” with medical assistance, but still a pandemic.

  17. Viruses in History • Applications in Biotechnology • Knowing what you do about how a virus replicates, why do you think scientists look to viruses to help treat genetic disorders?

  18. Unanswered Questions • Last remaining stores of smallpox in U.S. and Russia? • Herd immunity vs. individual freedoms - parents refuse vaccination for children? • Viruses used to modify genes for agriculture, medicine?

More Related