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Discovery of Viruses

Wendell Stanley Tobacco Leaf with Virus

Viral Characteristics

Ebola Picture
Ebola Virus

Viral Structure

Virus Structure

Bacteriophage Structure

Bacteriophages or T-Phages


HIV Virus


Viroid Attack on Potatoes


Lytic Cycle

Phases of the Lytic Cycle of a Virulent Virus: 

  1. Absorption: Virus attaches itself to the cell.
  2. Entry: Enzymes weaken the cell wall and nucleic acid is injected into the cell, leaving the empty caspid outside the cell. Many viruses actually enter the host cell intact.
  3. Replication: Viral DNA takes control of cell activity.
  4. Assembly: All metabolic activity of the cell is directed to assemble new viruses.
  5. Release: Enzymes disintegrate the cell in a process called lysis, releasing the new