Viruses

Just because I quack like a Duck! What? A small, nonliving particle that invade and then replicates inside a living cell. Non-living, does not have any characteristics of a living organism. Just because I quack like a Duck!

~ Viruses can only multiply when they are inside a living cell ~ Viruses can only multiply when they are inside a living cell. ~ Viruses require a host ~ Host Cells- living things that provide a source of energy for a virus or an organism ~ Viruses are like parasites because they cause harm, destroy the cells in which they multiply. Virus destroy the cell…..this is what the exploding bridge represents.

What’s in a name? Viruses do not belong to any living kingdom. They are named from organisms they infect, scientists that discover them, where they are found, or what symptoms they cause.

Virus Size Comparison http://www.youtube.com/watch?v=fUAFqkS7y9M Link shows that virus is the third smallest thing in the Universe. Narrate as the movie plays. Emphasis just how very small it is, and just how much damage it can do. http://www.youtube.com/watch?v=fUAFqkS7y9M

Multiplication x2 Lytic Cycle: Takes over genetic material of the cell. Cell is programed to produce the proteins and genetic material of the virus. This is then assembled as a virus. Kills the cell http://www.youtube.com/watch?v=Rpj0emEGShQ Lysogenic Cycle: Virus injects genetic material into living cell. It then becomes part of the cells genetic material. Now the cell is reproducing every cell with virus inside. When stressors to the body occur, the dormant virus activates moving into the Lytic cycle. http://www.youtube.com/watch?v=41aqxcxsX2w Explain that active or Lytic cycle is like the common cold. It comes in kills the cell, replicates then eventually fades out Non active/ dormant or Lysogenic Cycle is like Aids or Herpes. It becomes part of the cell. Therefore even if some cells move into the Lytic Cycle, the other cells are reproducing with more virus inside. You may be able to get rid of the symptoms, but the virus is now a part of you (never goes away)

Bacteriophage Virus that attacks prokaryotic cells (bacteria) Can be useful to kill disease causing bacteria or Can infect the good bacteria

Homework Explain why biologists consider viruses to be nonliving. Describe the basic structure of a virus. Compare the two ways that viruses can multiply. Scientists hypothesize that viruses could not have existed on Earth before organisms, such as bacteria, appeared. Use what you know about viruses to support this hypothesis.