Saturday, January 14, 2012

9. bacteria, virus, prion, protist

Bacteria are single cell organisms, with countless varieties that have different effect on the organisms. They have a wide range of shapes including spheres, rods, and spirals. These organisms can be found almost anywhere on Earth, from the skin on our body to the hair on our head. Plants and animals also have hundreds of thousands of bacteria living within and outside of them. One gram of soil can contain up to forty million bacteria cells in it.
Unlike bacteria, viruses are small infectious agents. Bacteria are able to be spread easily while viruses can only replicate inside human beings or other living cells of organisms. Besides human beings, they are able to infect all sorts of organisms from animals to plants to bacteria.
Another infectious agent is the prion. Prion is made up of a type of protein that is folded differently than a regular protein. They are able to transmit different diseases to organisms, similar to bacteria and viruses, including mad cow disease. Unlike some bacterial and viral diseases, prion infections are deadly because all the known prion diseases target the neural tissues including the brain. These diseases have no known cure.
Protists are a group of different eukaryotic microorganisms with a variety of different unicellular organisms. They are either uniceullular or multicellular without specialized tissues which makes them a lot more simple than the other organisms. The usually live in water which could also be in the human body. Some protists are beneficial to the human body and do not harm them like viruses and prions.

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