Viruses are non-living particles that affect all living things by spreading disease. Some familiar viral infections include: the common cold (my ailment of the week), influenza, measles, chicken pox, small pox, HIV, polio, ebola and many, many more.
Why are viruses not considered to be organisms? Viruses do not perform all of the characteristics of living things, though we may talk about them as being "alive". Viruses cannot grow. They do not require energy, use energy or release wastes, so viruses do not perform metabolic activities. They contain hereditary material (DNA or RNA) that is enclosed in a protein shell, but are not composed of cells. Viruses are also unable to respond to their environment. Though viruses can reproduce (in great numbers), they can only do so within a host cell.
Because viruses are not alive, they cannot be killed. Infections caused by viruses can be prevented by administering vaccines, which contain weakened forms of the virus itself. However, if you are unfortunate enough to contract a viral infection, treatment is tough. The symptoms of the infection can be treated (like taking a nasal decongestant to make your cold more tolerable), but medication will not take cure the disease and you will have to let your body fight it using your immune system. Certain viral infections can be fought by your immune system (like the flu and the cold), but others may be permanant and one may remain infected for life (like HIV, HPV and herpes). Whether a virus is easy to catch (like my cold!) or easily preventable (like HIV), our first defense against these infectious particles is our largest organ - our skin!
Important viral vocabulary words:
- virus
- vaccine
- host cell
- communicable
- bacteriophage
- antibodies
- immune system
Infections caused by bacteria and viruses differ through one major concept - bacterial infections can be treated with antibiotics, whereas viral infections cannot be "cured" through medication. Some viral infections can be prevented through vaccination (like Measles-Mumps-Rubella, chicken pox, the flu, polio).
Tuesday, October 30th is a big day for us. On this day:
- Bacteriophage projects are due
- Bacteria/Virus test will be administered
- Notebooks will be collected
On Wednesday and Thursday, we will conclude this unit by viewing one of my favorite highly scientific films...."Outbreak". I've seen it a gazillion times (no exaggeration) and still love it!
Don't forget to check out the previous post on how a bacteriophage attacks its host cell.....I think that it is soooo cool!
Study hard and have a great weekend!
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