1 / 26

Viruses

Adenovirus - cause of the common cold. Viruses. Viruses are  pathogens that attack cells from the inside.  They hijack your own DNA and use it against you.  A virus cannot be treated with antibiotics, it can only run its course until your immune system kicks it out.

abel-hammond
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. Adenovirus - cause of the common cold Viruses Viruses are pathogens that attack cells from the inside.  They hijack your own DNA and use it against you.  A virus cannot be treated with antibiotics, it can only run its course until your immune system kicks it out. ..Even then, the virus may lay dormant within the cells and come back at a later date Adapted from www.biologycorner.com

  2. Properties of viruses • no membranes, cytoplasm, ribosomes, or other cellular components • they cannot move or grow • they can only reproduce inside a host cell • they consist of 2 major parts - a protein coat, and hereditary material (DNA or RNA) • they are extremely tiny, much smaller than a cell and only visible with advanced electron microscopes

  3. Structure of DNA (review) Shape of a DOUBLE HELIX Each side held together by weak HYDROGEN BONDS Repeating units of NUCEOTIDES Sides of "ladder" are deoxyribose and phosphates Center is A, T, G, C A -> T G -> C         *base pair rule

  4. nucleotide

  5. Virus Structure

  6. Parasitic Nature  Obligate intracellular parasites (they cannot exist independently) Specific to hosts (human, dog, some can cross species)  Specific to cells , the common cold is a virus that specifically attacks cells of the respiratory track (hence the coughing and sneezing and sniffling). HIV specifically attacks white blood cells This is a bacteriophage, a type of virus that attacks bacteria. It is recognizeable because it looks like the lunar landing spaceship. See animation http://www.youtube.com/watch?v=41aqxcxsX2w&feature=related

  7. Viral Reproduction Lytic cycle = reproduction occurs, cells burstLysogenic cycle = reproduction does not immediately occur (dormancy) Virulent = viruses that undergo both cycles https://www.youtube.com/watch?v=Rpj0emEGShQ&feature=player_embedded

  8. Viruses multiply, or replicate using their own genetic material and the host cell's machinery to create more viruses. Viruses cannot reproduce on their own, and must infect a host cell in order to create more viruses. 1. Attachment 2. Penetration - the virus is engulfed by the cell                    (Cell can enter Lysogenic or Lytic Cycle) 3. Biosynthesis - viral components are made                        (protein coat, capsid, DNA/RNA) 4. Maturation - assembly of viral components 5. Release - viruses leave host cell to infect new cells                     (often destroys host)

  9. Lytic vs Lysogenic Pathways of viruses Starring the phage named Lambda See: http://highered.mcgraw-hill.com/sites/007352543x/student_view0/chapter20/lambda_phage_replication_cycle.html

  10. Retroviruses -- RNA viruses that have a DNA stage  • Human Immunodefiency Virus - causes AIDS  • Retrovirus (RNA inside a protein coat)  • Reverse Transcriptase makes DNA from the virus RNA  • DNA inserts into host DNA  • Proteins are assembled from the DNA code  • Viruses assembled from the proteins  • Viruses released from the cell (Link) HIV Animation - how virus infects cells

  11. What we know about HIV.....

  12. Developing a vaccine for AIDS is difficult because it is a RETROVIRUS.  RNA mutates easily and each individual virus can be slightly different from the others.  In fact, different viruses can exist within the same person. See:  HIV coloring

  13. Emerging Viruses  illnesses not previously known  AIDS, West Nile Virus, SARS, Ebola, Bird Flu  • Could be mutations of known viruses  • Could be viruses exposed when new areas were developed  • Could have jumped species (avian flu, swine flu)

  14. Related to Viruses Viroids - even smaller than viruses, consist of RNA strands that lack a protein coat Prions - "rogue protein", believed to be the cause of Mad Cow Disease, also may cause Kuru in cannibal tribes See:  http://highered.mcgraw-hill.com/sites/007352543x/student_view0/chapter20/how_prions_arise.html

  15. How Do Vaccines Work? 1.  Once you have gotten a virus, such as chicken pox, your body develops the immunity to that virus.   2. Vaccines are made by growing a weakened or killed form of the virus (often grown in eggs) 3.  This form of the virus is injected into a person's body, which causes an immune response, and immunity to the virus.    - Remember Jenner's cowpox vaccine?

  16. RV = rotovirus; DTaP = diptheria, tetanus, pertussis (whooping cough);  Hib = haemophilus influenza type B;  PCV = pneumococcal vaccine; IPV = inactivated polio virus;  MMR = measles, mumps, rubella,  

  17. INFLUENZA

  18. BACTERIOPHAGE

  19. H1N1

  20. SMALLPOX

More Related