virus biology life cycles

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Information about virus biology life cycles

Published on March 3, 2009

Author: rizwanahmed


Slide 1: Virus Replication Slide 2: Virus: A biological particle composed of nucleic acid and protein Intracellular Parasites: organism that must “live” inside a host What is a Virus? Slide 3: Is Fire Alive? 1) Made of cells? 2) Organization? 3) Require energy? 4) Respond to Environment? 5) Grow? 6) Reproduce? 7) Adapt? yes yes yes yes no no no Slide 4: Reproduce They have DNA or RNA They can adapt to surroundings The have organization They are not made of cells or organelles They cannot reproduce without a host They don’t have both DNA and RNA They do not metabolize energy Yes No Are Viruses Alive? Slide 5: All Have: 1) Capsid: coat of protein that surrounds DNA or RNA 2) Nucleic Acid: RNA or DNA Some Have: Tail Fibers: Used for attachment (not legs) Shapes vary Virus Parts Slide 6: Cannot reproduce w/o a host cell Virulent: cause disease Bacteriophages (infect bacteria) are often studied Replication is similar with many animal viruses Viral Replication Slide 7: 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 The Lytic Cycle Slide 8: 2nd Step: Entry Virus enzyme weakens cell membrane Genetic material (DNA or RNA) enters host cell The Lytic Cycle endocytosis Slide 9: 3rd Step: Replication Virus DNA/RNA uses ribosomes to make virus proteins Proteins created by transcription/translation Virus proteins make new virus parts The Lytic Cycle Slide 10: 4th Step: Assembly (formation) New virus parts are assembled in the cytoplasm The Lytic Cycle Slide 11: 5th Step: Lysis & Release Virus enzyme causes cell membrane to “lyse” New viruses are released to find new host Cycle repeats The Lytic Cycle Viral Transcription & Translation : Viral Transcription & Translation If DNA Virus: 1) Viral DNA injected 2) Viral DNA transcribed into viral mRNA 3) Viral mRNA translated into viral proteins If RNA Virus: 1) Viral RNA injected 2) Viral mRNA translated into viral proteins Slide 13: 1st step: Attachment = Same The Lysogenic Cycle 2nd Step: Entry = Same Slide 14: 3rd step: Replication Virus DNA combines with cell DNA, and waits… Cell divides as usual Each new cell will have virus DNA inside Lysogenic Cycle Slide 15: 4th Step: Assembly Same, except many new viruses are being assembled in many cells The Lysogenic Cycle 5th Step: Release Same, except many cells “lyse” releasing many more viruses Retroviruses : Retroviruses Type of RNA virus that contains the enzyme Reverse Transcriptase 1) Virus RNA is injected into cell 2) Ribosome uses virus RNA to create virus DNA 3) Virus DNA combines with cell DNA (becomes latent) 4) Once active, normal steps of transcription/translation followed How isHIVContracted? : How isHIVContracted? 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 Prevention : Prevention 100% Effective: Abstinence (not participating in sexual acts) If sexually active: Latex condoms effective when used properly Fact: Latex condoms are the only forms of birth control that protect against STDs If drug user: Change needles Slide 19: AIDS Quilt 3ft x 6ft quilt panel can be created as a memorial tribute Slide 20: Panels from across the world are sewn together AIDS Quilt Slide 21: Panels travel around the world to help remember and raise awareness AIDS Quilt Slide 22: Over 44,000 panels exist today AIDS Quilt

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