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Virus Replication

Virus Replication. What is a Virus?. Virus : A biological particle composed of nucleic acid and protein Intracellular Parasites : organism that must “live” inside a host. Reproduce Have nucleic acid Adapt to surroundings Have organization. Not made of cells or organelles

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Virus Replication

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  1. Virus Replication

  2. What is a Virus? • Virus: A biological particle composed of nucleic acid and protein • Intracellular Parasites: organism that must “live” inside a host

  3. Reproduce Have nucleic acid Adapt to surroundings Have organization Not made of cells or organelles Can’t reproduce on own Don’t metabolize energy Don’t perform cellular processes Are viruses alive? No Yes

  4. Virus Parts • All Have: • 1) Capsid: coat of protein that surrounds nucleic acid • 2) Nucleic Acid: RNA or DNA • Some Have: • Tail Fibers: Used for attachment (not legs) • Shapes vary

  5. Viral Replication • Bacteriophages (infect bacteria) are often studied • Replication is similar with many animal viruses

  6. The Lytic Cycle 1st Step: Attachment • Virus lands on cell membrane • Virus attaches to a cell receptor • No attachment = No infection • Virus acts as a “key” to the receptor

  7. The Lytic Cycle 2nd Step: Entry • Virus enzyme weakens cell membrane • Genetic material (DNA or RNA) enters host cell endocytosis

  8. The Lytic Cycle 3rd Step: Replication • Virus DNA/RNA uses ribosomes to make virus proteins • Virus proteins created by transcription/ translation

  9. The Lytic Cycle 4th Step: Assembly • New virus proteins are assembled in the cytoplasm

  10. The Lytic Cycle 5th Step: Release • Virus enzyme causes cell membrane to burst • Viruses are released to find new host • Cycle repeats

  11. The Lysogenic Cycle 1st step: Attachment = Same 2nd Step: Entry = Same

  12. Lysogenic Cycle 3rd step: Replication • Virus DNA combines with cell DNA, and waits • Provirus = cell DNA + viral DNA • Cell divides by mitosis • Each new cell will contain the provirus

  13. The Lysogenic Cycle 4th Step: Assembly Same, except many new viruses are being assembled in many cells 5th Step: Release Same, except many cells burst releasing many more viruses

  14. RNA viruses Contains the enzyme Reverse Transcriptase Steps 1) Virus RNA enters host cell 2) Cell’s ribosomes create virus DNA 3) Virus DNA combines with cell DNA (becomes dormant) 4) Cells divide as usual 5) Once active, normal steps of transcription/translation followed Retroviruses

  15. High risk activities: 1) Sex (oral, vaginal, anal) 2) Sharing needles (tattoos, piercings, drugs) Low risk activities: 3) Mother to child in womb 4) Breast milk 5) Blood transfusions How is HIV contracted?

  16. New Exposures to HIV (2006) What is AIDS? Gender of those living with HIV (2003) • Acquired Immunodeficiency Syndrome • AIDS results when: • 1) Less then 200 T cells per 1mm³ blood • 2) Multiple symptoms/infections from HIV appear • Therefore, the HIV virus causes the disease AIDS

  17. Female Transmission of HIV (2006) Male Transmission of HIV (2006) Want more stats? Go to the Centers for Disease Control’s Website http://www.cdc.gov/hiv/topics/surveillance/united_states.htm

  18. AIDS Quilt 3ft x 6ft quilt panel can be created as a memorial tribute

  19. AIDS Quilt Panels from across the world are sewn together

  20. AIDS Quilt Panels travel around the world to help remember and raise awareness

  21. AIDS Quilt Over 44,000 panels exist today

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