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  1. 1. By iTutor.comT- 1-855-694-8886Email-
  2. 2. Virus – structure & function Viruses are microscopic particles which Do not grow / mature Are parasitic, onlyreproducing within a living organism
  3. 3. Where do Viruses Come From? They’ve been around for at least4000 yeas. Small Pox First virus in recordedhistory Pharoah Ramses V (1196B.C.) had the pot marks associatedwith small pox.
  4. 4. (1) Evolved from Cells Some cells evolved into viruses: By losing their genetic materials, thus requiring thegenetic material of host cells When fragments of a cell’s DNA combined to makesomething new (a virus)(2) Evolved with Cells Simple molecules on earth evolved into: Cells which have self-replicating abilitiesor Viruses which have parasitic abilities, using cells to reproduce.Three Theories on Viruses
  5. 5. Three Theories on Viruses Idea that viruses came to Earth via a meteor Why sucha strange idea? Viruses are so different from everything else onEarth.(3) Alien Theory
  6. 6. • Viruses are simple structures consisting of1. Capsid• A protein coat made of individual protein subunitscalled capsomeres.• Provides the virus with its shape• Makes up 95% of a virus’s sizeVirus – structure & function2. Genetic Material• Genetic material is located inside the capsid.• Can be DNA or RNA
  7. 7. Virus – structure & function
  8. 8. 1. Spikes• Located on capsid• Helps viruses attach to cells• Not present on all viruses2. Envelope• Above capsid• A protective coat on somevirusesVirus – structure & function
  9. 9. Viruses & Human Health Many serious diseases are causedby viruses Symptoms are caused bydestruction of the cell the virusesinfect Antibiotics are not effective againstviruses Viral diseases can be prevented with vaccines The body reacts to the vaccine as though it were the realdisease and produces antibodies
  10. 10. How are viruses transmitted? Breathing in air-bornedroplets contaminatedwith a virus. Eating food or drinkingwater contaminated witha virus. Having sexual contactwith a person who isinfected with a sexuallytransmitted virus. Indirect transmission from person to person by a virushost, such as a mosquito, tick, or field mouse. Touching surfaces or body fluids contaminated with a virus.
  11. 11. Diseases caused by viruses Smallpox This variola virus had many forms andcontinues to be a required vaccination. Smallpox in its worse forms– hemorrhagic–flat – had the highest fatality rates withonly a 10 percent or less chance of survival. Cancer Viral cancers only occur in a minority ofinfected persons (or animals). Cancer viruses come from a range of virusfamilies, including both RNA and DNAviruses.
  12. 12. Diseases caused by viruses AIDS has been categorized as an epidemicby the CDC and the life expectancy hasbeen extended despite the lack of avaccination or cure. The Ebola virus is much more deadly in theshort term. Polio or infantile paralysis is a viraldisease that is transmitted through thefecal-oral course HIV / AIDS Human immunodeficiency virus (HIV) leads to acquired immunedeficiency syndrome (AIDS), which cripples a human’s immunesystem.
  13. 13. Vaccines This is a prepared virus that has been HEATED tokill/destroy the genetic material while leaving the capsid(protein coat) intact. Vaccine is injected into a host, to trigger the immunesystem. Immune system builds antibodies specific to that virus.
  14. 14. The EndCall us for more information:www.iTutor.com1-855-694-8886Visit