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Viruses ppt
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- 2. It’s a SmallWorld • Virus: a microscopic particle that gets inside a cell and often destroys the cell • Viruses are tiny • Smaller than the smallest bacteria • Change rapidly • So small and change so often that scientists don’t know exactly how many types exist • These properties make viruses difficult to fight
- 4. Are Viruses Living? •Like living things, viruses contain protein and genetic material • But viruses don’t act like living things • Can’t eat, grow, or break down food • Can’t use oxygen • Cannot function on its own
- 5. • Can onlyreproduce inside a living cell that serves as a host • Host: an organism from which a parasite takes food or shelter • Virus uses host’s cell as a tiny factory, and forces host to make viruses rather than healthy new cells
- 6. • Can begrouped Classifying Viruses together by: • Their shape • Type of disease they cause • Life cycle • Kind of genetic material they contain • There are 4 main shapes of viruses:
- 7. Crystals: The poliovirus is shaped like the crystal shown here. Cylinders: The tobacco mosaic virus Is shaped like a cylinder and attacks tobacco plants.
- 8. Spheres: Influenza viruseslook like spheres. HIV is another virus that has this structure. Spacecraft: One group of viruses attacks only bacteria. Many of these look almost like spacecraft (also called Bacteriophage).
- 9. • Every virusis made up of genetic material inside a protein coat (also known as capsid) • The protein coat protects the genetic material and helps a virus enter a host cell • Many viruses have protein coat that matches characteristics of their specific host • There are 4 main shapes of viruses: crystals, spheres, cylinders, and spacecraft Capsid: protein coat that surrounds virus
- 12. Genetic Material • Geneticmaterial either DNA or RNA • Most RNA is made up of one strand of nucleotides, most DNA is two strands of nucleotides • Both DNA and RNA contain info for making proteins • Example: viruses that cause chickenpox & warts contain DNA • Example: viruses that cause flu, HIV, and common cold contain RNA
- 13. • One strainof virus cannot infect both plants and animals Virus Affects Which organisms? What? Tobacco mosaic Plants Tobacco, tomato, peppers Potato X Plants Potatoes, tomatoes, peppers Adenovirus Animals Humans & other vertebrates HIV Animals Humans & other primates Bacteriophage Bacteria E.Coli & other bacteria
- 14. Different Kinds ofViruses & their sizes
- 15. Chicken pox (Varisellazoster virus Flu (Influenza virus) (VZV) Rabies virus
- 16. A Destructive HouseGuest • One thing that viruses do that living things also do is make more of themselves • Viruses attack living cells and turn them into virus factories • The cycle if a virus incorporating its genes into the genes of a host cell is called : THE LYTIC CYCLE
- 18. A Time Bomb •Some viruses don’t go straight into lytic cycle—they put genetic material in host cells, but don’t make new viruses right away • In the lysogenic cycle, each new cells gets a copy of the virus’s genes when the host cell divides • The genes stay inactive for a long time • When they do become active, they begin the lytic cycle and make copies of the virus
- 20. Treating a Virus •Antibiotics don’t kill viruses • Scientists have developed antiviral medications • Because many viral diseases do not have a cure, it is best to prevent a viral infection from happening in the first place
- 21. • Childhood vaccinations give your immune system a “head start” on fighting viruses • Vaccinations need to be kept current • Also a good practice to always wash your hands