VIRUS WANTED: Dead or Alive (or otherwise)

Variety of Viruses Viruses are a unique phenomenon of nature They come in diverse shapes and sizes and affect all forms of life; including animals, plants and bacteria!

Its ALIIIIIVE! Or is it??? Are viruses living creatures? -Contain nucleic acids, DNA and RNA -Consist of walls, membranes, tails, proteins -Adapt to environments and stresses through genetic mutations, leading to evolution -Reproduce* bacteriophageInfluenza virus Tobacco Mosaic Virus

Not So Alive After All! or are they?? Are Viruses Non-Living Creatures? -NOT cellular, only composed of nucleic acids and proteins -Walls are called ‘protein coats’ -Can not reproduce independently -Require a host cell to complete reproductive cycle

Right Virus for the Right Job Viruses mean business –Protein coat that fits in with the host cell wall/membrane and short DNA/RNA that can be replicated quickly Viruses are designed and classified based on the type of cell they attack –The proteins in the coat of each virus act as keys that unlock the door to a specific cell type Ie: HIV virus, only infect fighter T cells of the human immune system Ie: cold virus infects cells of the soft palate Ie: bacteriophage virus infects certain bacterial cells (used in biotechnology!)

Famous Viruses

Viral Reproduction Viruses can not reproduce on their own, they need to infect a host cell to complete their reproductive phase Two phases: Lytic and Lysogenic cycles –Lytic cycle is a phase of rapid reproduction, destruction and further infection Invade a cell, take over, make copies, burst the host cell and move on –Lysogenic cylce is a type of dormant phase, the viral DNA is incorporated into the host cell DNA –Replicated through traditional mitosis –Upon a stressor the viral DNA breaks out of the host DNA, and starts up a lytic cycle

Viral Reproduction