Essay - In Search of the Perfect Host the Origins and Specificity...

In Search of the Perfect Host

The Origins and Specificity of Parasites

The door opens. You walk into the room. You hear your favorite music. You see your best friends. Your favorite drink is waiting on the bar. Smiling, the hostess approaches, "I did it all for you." Ah, what a dream - ***** perfect party, the perfect host! While such a fantasy may not always be the lot of ***** human guest, it is real life for many microbial vis*****ors. Every parasite has its "***** host," the one organism that is ideally suited to its needs. Of course, this perfect pairing of guest and host ***** not evolve by accident. Over ***** course of time, parasites have evolved in tandem with the *****s upon which they live. It is a unique relationship, the ***** organ*****m providing a complete environment ***** ***** parasite. The parasite ***** so completely adapted itself to the conditions of particular host species that it can ***** nowhere else. Dirofilaria immitis, or ***** Canine Heartworm, goes through its entire life cycle ********** the body of a dog. Hymenolepis diminut***** is a tapeworm of rodents. And Enterobius vermicularius is a pinworm ***** infects humans. In each of these examples, the parasite has become adapted to living in a particular part or parts of ***** host *****ganism. It feeds, reproduces, and eventually dies inside the bloodstream, organs, or cells ***** its unwilling *****.

***** how did such organisms evolve? And how ***** they ***** so specifically attuned to the physiology of their host species?

***** order to find the answers to these questions, it is necessary to turn back the evolutionary clock and to look at ***** origins of life *****. The most prim*****ive ***** forms all shared similar structures, the ancestral ***** of those structures that today compromise the typical cell. As it still does *****, Ribonucleic Acid, or RNA, served ***** purpose ***** regulating the life-functions w*****hin the cell. A simpler form of DN*****, to ***** it is closely related, RNA was most likely the early bas***** of life.

RNA serves a multitude of roles in liv*****g cells. *****se include: serving ********** a temporary copy ***** genes that is used as a templ*****te for protein synthesis (mRNA), functioning as adaptor molecules that decode the genetic code (tRNA) and catalyzing ***** ***** of proteins (rRNA). There is much evidence implicating RNA structure in biological regulation ***** catalys*****. Interest*****gly, RNA is the only biological polymer that serves as both a *****t (like proteins) and as in*****mation storage (***** *****A). For ***** reason, it has be postulated RNA, or an RNA-like molecule, was the basis of life early in evolution." (Murthy, 2002)

In addition to performing the above functions in all *****, RNA is essential ***** ***** operation of parasitic microbes. Specifically, it is the *****'s ability to make copies ***** itself, and in fact to alter those copies according to ***** genetic *****-up of its host, ***** enables the ***** to function within its ***** organism. While the