Viruses Flashcards
Why Care?
Causes human diseases (ex. common cold, HIV, rabies, COVID-19) and some also play a role in certain types of cancers (ex. HPV)
What are viruses?
Has either DNA or RNA protected by a protein coat called a capsid –> viruses aren’t classified in any kingdom because they aren’t cells and are only living when in another cell - considered non-living structures
About 4000 classified, but believe there may be millions
Virus Classification
Mainly classified by phenotypic characteristics:
1. Morphology (shape)
2. Nucleic acid type (DNA or RNA)
3. Method of reproduction (lytic or lysogenic)
4. Host organism
5. Type of disease caused
How it Spreads
Insects: organisms that carries/spreads a disease called a vector (eg. yellow fever spread by type of mosquitoes)
Animals (eg. rabies spread by biting)
Water: sewage treatment doesn’t kill viruses, some end up in lakes and rivers (eg. polio)
Global Spread: with advances in travel, spread of a disease over the world has increased - worldwide epidemics can occur any time
Epidemic
Large scale outbreak but is limited to a specific geographic location
Pandemic
Over a widespread geographic area and sometimes over the entire world
Lytic Cycle
Can take less than an hour start to finish
Virus attaches to surface of bacterium and injects its genetic material into the bacterium. The cell starts producing the virus’ proteins and genetic material then assembles them into new viruses. The bacterium bursts, releasing the new viruses.
Lysogenic Cycle
Can last for years
Virus attaches to surface of bacterium and injects its genetic material into the bacterium. The virus’ genetic material becomes part of the bacterium’s genetic material. After some time, it separates and becomes active. This causes the cell to produce the virus’ proteins and genetic material then assemble them. The bacterium bursts, releasing the new viruses.
