VIRUSES!

1. VIRUSES!

2. We have all gotten viruses… from bacteria, plants to animals. Viruses cause colds, flu, warts and diseases such as measles, AIDS and cancer. BUTnot all viruses cause diseases, AND not all viruses are harmful to humans. Introduction – Structure – Replication – Virology – Medicine - Review

3. WHAT IS A VIRUS? Introduction – Structure – Replication – Virology – Medicine – Review

4. A VIRUS is either DNAorRNA, that is protected by a protein coat called a CAPSID. DNA CAPSID VIRUS Introduction – Structure – Replication – Virology – Medicine - Review

5. Why are some viruses harmful? Virus invades cell When your cells make viruses instead of operating normally, YOU get sick Virus forces cell to make copies of virus Eventually so many copies are made, the cell explodes, releasing all of the new viruses Introduction – Structure – Replication – Virology – Medicine - Review

6. Examples of some viral diseases: Introduction – Structure – Replication – Virology – Medicine - Review

7. Who do viruses infect? • Viruses infect Bacteria • These viruses are called bacteriophages • Viruses infect Plants • One example is the Tobacco Mosaic Virus • Viruses infect Animals • One example is the common cold Viruses usually infect a specific host including: Introduction – Structure – Replication – Virology – Medicine - Review

8. Let’s look at the Defining Properties of Viruses • Viruses are parasites that invade cells • Viruses have either DNA (Deoxyribose Nucleic Acid)or RNA (Ribonucleic Acid) • Viruses direct the synthesis of new virus within a host cell. • Newly made viruses infect other cells. Introduction – Structure – Replication – Virology – Medicine - Review

9. Cell Biology Let's review a little cell biology since viruses cannot multiply without the help of cells. The viruses enter the cell and forces the cell to make more viruses. nucleus The cell has three main zones: Nucleus – this holds the DNA or genetic information about the cell. Cytoplasm – this is the “factory” where biochemical reactions occur. Membrane – this double layer protects the cell and allows the cell to communicate with the outside environment. membrane cytoplasm Introduction – Structure – Replication – Virology – Medicine - Review

10. DNA/RNA DNA or RNA code for genes that defines who we are. DNA, deoxyribonucleic acid, is the double-stranded molecule that encodes genetic information (e.g. your hair color, height, etc.) in the nucleus of cells. The complete set of DNA in a cell is called the genome. RNA, ribonucleic acid, is typically single stranded so that it can be read to make proteins. Introduction – Structure – Replication – Virology – Medicine - Review

11. How small is a virus? Introduction – Structure – Replication – Virology – Medicine - Review

12. Viruses range in size from 20 nanometers (nm) – 250 nanometers (nm) 1 nm = 0.00000004 inches If a cell was the size of your classroom, then an average virus would be the size of a softball. proteins animal cells atom bacteria viruses 0 m 10-5 m 10-6 m 10-7 m 10-8 m 10-9 m Go five more feet! 10-10 m

13. Helical Capsids RNA Helical capsids are rod-like structures with the RNA in the center of the helix. A helix is made by stacking repeating units in a spiral. protein coat Introduction – Structure – Replication – Virology – Medicine - Review

14. Tobacco Mosaic Virus Tobacco Mosaic Virus (TMV) is an example of a virus with a helical structure. Protein subunits wrap around the spiraling RNA strand. This image taken using an Electron Microscope Introduction – Structure – Replication – Virology – Medicine - Review

15. Adenovirus Adenoviruses cause diseases like pink-eye or the common cold Introduction – Structure – Replication – Virology – Medicine - Review

16. Bacteriophage Bacteriophage is a virus that infects bacteria. Introduction – Structure – Replication – Virology – Medicine - Review

17. Enveloped Viruses Enveloped viruses are viruses which have a membrane coat surrounding the protein coat or capsid. These viruses are common in animal viruses, but are uncommon in plant viruses. Herpes Simplex Virus. A membrane (made of proteins) surrounds the capsid (also made of proteins) which surrounds the viral DNA. Introduction – Structure – Replication– Virology – Medicine - Review

18. How do viruses replicate? Introduction – Structure – Replication – Virology – Medicine - Review

19. Replication Phases • I, II, III - Viruses enter cell • Attachment to cell membrane • Penetration inside cell • Losing virus protein coat Phase I V - Release • Assembly of virus DNA and protein coat into whole new viruses • Leaving the cell • IV - Replication • Tricks cell into making more viral DNA • Tricks cell into making viral protein coat Phase II Phase III Phase V Phase IV http://www.cat.cc.md.us/courses/bio141/lecguide/unit2/viruses/adlyt.html Introduction – Structure – Replication – Virology – Medicine - Review

20. The concept of a virus as an organism challenges the way we define life: * Viruses do not breathe. * Viruses do not metabolize. * Viruses do not grow. * However, they do reproduce. Introduction – Structure – Replication – Virology – Medicine - Review

21. Are Viruses Living? Create a table where one column represent properties of living organisms and the second column represent properties of a virus. Introduction – Structure – Replication – Virology – Medicine - Review

22. Viruses Can Help Cells, Too • Since viruses can transport DNA and RNA into cells, scientists are exploring GeneTherapy • In Gene Therapy, viral genetic material is replaced with new DNA • In time, this could be used to cure genetic diseases. Currently we have no cure for these types of illnesses Introduction – Structure – Replication – Virology – Medicine - Review

23. - Viruses, Bacteria, and Your Health Common Viral Diseases • Unlike with bacterial diseases, there are currently no medications that can cure viral infections.

24. The End! And Review • Viruses are very simple: a shell containing either DNA or RNA. They infect by hijacking cells’ machinery to force them to make more viruses. • Viruses are tiny, even compared to a cell. • Some viruses may prove useful in gene therapy as natural carriers of DNA that was specially designed to be good for a particular reason. Introduction – Structure – Replication– Virology – Medicine - Review

25. The End Introduction – Structure – Replication– Virology – Medicine - Review