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Viruses

Viruses. We have all gotten viruses… from bacteria, plants to animals. Viruses cause colds, flu, warts and diseases such as measles, AIDS and cancer. BUT not all viruses cause diseases,. AND not all viruses are harmful to humans. Viruses.

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Viruses

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  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.

  3. Viruses • Submicroscopic bodies which reproduce within living cells.

  4. Viruses • Submicroscopic bodies which reproduce within living cells. • Biological particle that is composed of genetic material and protein.

  5. A VIRUS is either DNA orRNA, that is protected by a protein coat called a CAPSID. DNA CAPSID VIRUS

  6. 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

  7. Can antibiotics be used to cure an illness caused by a virus?

  8. Can antibiotics be used to cure an illness caused by a virus? • Antibiotics have no effect on viral infections. Antibiotics only work on Bacterial infections. • This is why the doc will not give you antibiotics for the flu or a cold.

  9. Do viruses qualify as living things? • Virus do not grow. • They have no nucleus, cytoplasm, or membranes. • They do not carry out cellular functions. • Virus do not generate metabolic energy. • They are obligate intracellular parasites, meaning that they require a host cell to reproduce.

  10. Do viruses qualify as living things? • So, Viruses are considered non-living.

  11. Viruses can be harmful. • Virulent - disease causing. • Temperate - not immediately disease causing.

  12. Viruses may be helpful. • A temperate virus introduces nucleic acid (DNA) from its former host into a new host, thus changing the genetic code of the host.

  13. Viruses may be helpful. • A temperate virus introduces nucleic acid (DNA) from its former host into a new host, thus changing the genetic code of the host. • By this process, viruses cause genetic variation within a host population. • Are genetic differences good or bad????

  14. 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

  15. Type of nucleic acid • viruses have either single-strand RNA or double-strand DNA, but never both.

  16. Physical structure • viruses are found in several general shapes.

  17. Assignment • You are required to build a model of a bacteriophage and label all its parts • This is a 50 point assignment

  18. Herpes virus

  19. Herpes Simplex (Cold Sores) • Herpes simplex is a viral infection that attacks the skin and nervous system, and usually produces small, irritating and sometimes painful fluid-filled blisters on or around the mouth and nose.

  20. Herpes Simplex (Cold Sores) • Herpes simplex is caused by a virus, herpes simplex 1

  21. Herpes Simplex (Cold Sores) • Herpes simplex is caused by a virus, herpes simplex 1 • After the initial outbreak, the virus usually lies dormant in the skin or in nerve tissue until something triggers another eruption. 

  22. Herpes Simplex (Cold Sores) • Herpes simplex is caused by a virus, herpes simplex 1 • After the initial outbreak, the virus usually lies dormant in the skin or in nerve tissue until something triggers another eruption.  • Often the trigger is unknown, but in some people overexposure to sunlight, fever, physical or emotional stress, hormonal changes such as pregnancy or menstruation, or certain foods and drugs seem to reactivate the virus.

  23. Chicken Pox: Herpes Simplex

  24. Chicken Pox- Herpes

  25. Chicken Pox

  26. Genital Herpes • You catch Genital Herpes by unprotected sexual contact. • Genital Herpes is Herpes simplex

  27. Genital Herpes • You catch Genital Herpes by unprotected sexual contact. • Genital Herpes is Herpes simplex • Once you catch it, you have it forever. • 1-5 people have genital herpes. • Don’t catch it!

  28. FOREVER

  29. Genital Herpes • You catch Genital Herpes by unprotected sexual contact. • Genital Herpes is Herpes simplex • Once you catch it, you have it forever. • 1-5 people have genital herpes. • 50 million of Americans are reported to have been infected • Wanna see!!!!!

  30. No way, way to sick to show. • http://www.health-science-report.com/cgi-bin/alotek.cgi?topics=5&article=203 • The rate of genital herpes is higher in the poor, uneducated, and those who neglect safe sex rules. • Protect yourself

  31. Hepatitis B virus Hepatitis B virus causes both acute and chronic liver infections in man.

  32. Influenza virus

  33. Rotavirus Rotaviruses infect the lining of the intestine and cause diarrhea, especially in children.

  34. Type of host cell • most viruses are very specific about the type of cell they invade. • There are specific sites called receptor sites that the viruses attach to on the host cell's surface.

  35. Phases of the Lytic Cycle of aVirulentVirus: • Absorption: Virus attaches itself to the cell.

  36. Phases of the Lytic Cycle of aVirulentVirus: • Absorption: Virus attaches itself to the cell. • Entry: Enzymes weaken the cell wall and nucleic acid is injected into the cell, leaving the empty caspid outside the cell.

  37. Phases of the Lytic Cycle of aVirulentVirus: • Absorption: Virus attaches itself to the cell. • Entry: Enzymes weaken the cell wall and nucleic acid is injected into the cell, leaving the empty caspid outside the cell. • Replication: Viral DNA takes control of cell activity.

  38. Phases of the Lytic Cycle of aVirulentVirus: • Absorption: Virus attaches itself to the cell. • Entry: Enzymes weaken the cell wall and nucleic acid is injected into the cell, leaving the empty caspid outside the cell. • Replication: Viral DNA takes control of cell activity. • Assembly: All metabolic activity of the cell is directed to assemble new viruses.

  39. Phases of the Lytic Cycle of aVirulentVirus: • Absorption: Virus attaches itself to the cell. • Entry: Enzymes weaken the cell wall and nucleic acid is injected into the cell, leaving the empty caspid outside the cell. • Replication: Viral DNA takes control of cell activity. • Assembly: All metabolic activity of the cell is directed to assemble new viruses. • Release: Enzymes disintegrate the cell in a process called lysis, releasing the new viruses.

  40. The Lytic Cycle(a) Before attachment.  (b) Attachment.  (c) Penetration and uncoating.  (d) Replication.  (e) Assembly.  (f) Release.

  41. Rabies is an infectious viral disease that affects the nervous system of humans and other mammals. • People get rabies from the bite of an animal with rabies. • Any wild mammal, like a raccoon, skunk, fox, coyote, or bat, can have rabies and transmit it to people.

  42. The big brown bat is found throughout most of the United States and Canada. It feeds principally on beetles.

  43. Rabies: Case study • In February 1995, the aunt of a 4-year-old girl was awakened by the sounds of a bat in the room where the child was sleeping. The child did not wake up until the bat was captured, killed, and discarded. The girl reported no bite, and no evidence of a bite wound was found when she was examined. One month later the child became sick and died of rabies. The dead bat was recovered from the yard and tested--it had rabies. • This case demonstrates several points: • This child's infection with rabies was most likely the result of a bat bite. Children sleep heavily and may not awaken from the presence of a small bat. A bat bite can be superficial and not easily noticed. • The bat was behaving abnormally. Instead of hiding, the bat was making unusual noises and was having difficulty flying. This strange behavior should have led to a strong suspicion of rabies. • If the bat had been submitted for rabies testing, a positive test would have led to life-saving anti-rabies treatment.

  44. The Lysogenic Cycle of aTemperateVirus: • The virus attaches itself and injects its DNA into the cell.

  45. The Lysogenic Cycle of aTemperateVirus: • The virus attaches itself and injects its DNA into the cell. • The viral DNA attaches itself to the host DNA, becoming a new set of cell genes called a prophage.

  46. The Lysogenic Cycle of aTemperateVirus: • The virus ATTACHES itself to the host • INJECTS its DNA into the cell. • The viral DNA attaches itself to the host DNA, becoming a new set of cell genes called a prophage. • When the host cell divides, this new gene is replicated and passed to new cells. This causes no harm to the cell, but may alter its traits.

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