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Viruses

Viruses. Viral structure. Viruses are not cells . Viruses are not considered living. (cannot reproduce by themselves- must use a HOST) Basic structure: Protein coat-CAPSULE or CAPSID Nucleic acid core (RNA or DNA) -ENVELOPE- outside protein coat in some viruses. HIV VIRUS.

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Viruses

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  1. Viruses

  2. Viral structure • Viruses are not cells. Viruses are not considered living. (cannot reproduce by themselves- must use a HOST) • Basic structure: • Protein coat-CAPSULE or CAPSID • Nucleic acid core (RNA or DNA) • -ENVELOPE- outside protein coat in some viruses

  3. HIV VIRUS

  4. Virus Categories • DNA viruses – stable, do not mutate rapidly • Single-stranded or double-stranded • Smallpox, Hepatitis B • RNA viruses – mutate rapidly, unstable • Single-stranded or double-stranded • HIV, Rhinovirus

  5. Viruses are host specific – a protein on the surface of the virus (GLYCOPROTEIN) has a shape that matches a molecule in the plasma membrane of its host, allowing the virus to lock onto the host cell.

  6. LYTIC CYCLES Attachment Step 1 Step 3 Release Assembly Step 2 Replication

  7. LyticCycle (VIRULENT- or fast acting) STEP 1-Virus attaches to host cell’s membrane and injects its nucleic acid into the host cell. STEP 2- The viral nucleic acid takes over protein synthesis, creating new viruses. (can infect DNA or go straight to the ribosomes) STEP 3- The host cell bursts, LYSES, releasing the newly formed viruses.

  8. The Lysogenic Cycle

  9. LYSOGENIC CYCLE- TEMPERATE VIRUS or slow acting STEP 1-Virus attaches to host cell’s membrane and injects its nucleic acid into the host cell. STEP 2- Virus cuts into DNA and becomes part of the cell STEP 3- When cell reproduces so does the virus (DORMANCY)- STEP 4- LYTIC STAGE when stimulus is right

  10. How are viruses spread? AIR FOOD /WATER SEXUALLY TRANSMITTED SOIL

  11. KINDS OF VIRUSES

  12. HIV is a retrovirus injecting the enzyme, reverse transcriptase into the cell to copy viral RNA into DNA.

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