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Viruses

Viruses. Do you think a virus is a living cell?. Use the picture and this information to help you make your decision: Viruses contain RNA or DNA Viruses cannot replicate on their own, they must use a host cell to replicate and survive

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Viruses

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  1. Viruses

  2. Do you think a virus is a living cell? • Use the picture and this information to help you make your decision: • Viruses contain RNA or DNA • Viruses cannot replicate on their own, they must use a host cell to replicate and survive • Viruses do not contain ribosomes or any other type of organelle

  3. Are viruses alive? NO! Viruses cannot perform cellular processes or replicate without a host organism so scientists have classified them as non-living organisms.

  4. What types of organisms can viruses infect? Anything that is made of cells! • Plants • Animals • Bacteria • But – viruses are very species specific! • HIV - human white blood cells • SIV - chimpanzees white blood cells bacteriophage - bacteria cells

  5. Virus Structure Virus Structure: All viruses contain: 1. Protein Coat (Capsid) -protects genetics information -recognizes host cell 2. Nucleic Acid (DNA or RNA) -contains genetic information Influenza Virus HIV Virus H1N1 Virus

  6. Herpes Virus

  7. AIDS VIRUS (HIV)

  8. Viral Replication:The Lytic Cycle of bacteriophage 1. Virus attaches to host cell and inserts it’s DNA 2. Virus directs host cell to synthesize proteins and nucleic acids (DNA/RNA) 3. Newly created virus components (DNA/RNA, protein coat) are assembled to form new virus particles 4. Cell lysis: Host Cell explodes releasing newly synthesized viral particles ***** The lytic cycle results in death of the host cell!******

  9. Sneaky viruses Sneaky Viruses Some viruses are lysogenic • They insert their genetic material into the host cell’s DNA for long periods of time. Years, even! • Every time the host cell copies its DNA it makes a copy of the virus DNA as well. • The virus may switch to the lytic cycle at any time. • Examples include: herpes (cold sores), shingles, warts, HIV/AIDS

  10. Can viruses be helpful? • Viruses are sometimes used to attack bacteria that cause disease. For example, bacteriophages destroy bacteria, but not human cells • Viruses insert “good genes” into people with genetic diseases. This is called gene therapy. • Viruses are used to create genetically modified foods. They introduce desired traits (genes) into plants and animals.

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