virus life cycles

• Lytic cycle:

  1. Virus attaches to host cells.
  2. Virus enters cell and injects its DNA/RNA into the cell.
  3. DNA/RNA and virus proteins are packed together to make new viruses. They are released from the host cell which destroys it.
  4. Virus DNA/RNA copies itself and causes new virus proteins to be made, using the organelles in the host cell.
• Lysogenic cycle:

  1. Virus inserts its DNA into the chromosomes of the host cell. It is called a provirus.
  2. The provirus replicates with the rest of the host DNA every time the host cell divides.
  3. The provirus can become active and make new viruses in the lytic cycle.
• Virus:

  • No cellular structure but have a protein coat.

  • Contain one type of nucleic acid, either DNA or RNA

  • Small particles

  • Parasitic and can only reproduce inside living cells
• Viruses have no cell organelles so they are not living cells.