Viruses: Complex Molecules Or Simple Life Forms? :: essays research papers

Viruses Complex Molecules or Simple Life Forms?Viruses have been defined as "entities whose genomes ar elements ofnucleic acid that replicate inside living cells using the cellular syntheticmachinery, and cause the synthesis of specialised elements that can transfer thegenome to early(a) cells." They argon stationaryand are unable to grow. Because ofall these factors, it is debatable whether viruses are the most complex ofmolecules or the simplest life forms. While the definition of living organismsmust be adapted, the majority of evidence leads to the classification of virusesas living organisms.Viruses are composed of a nucleic acid core, a protein capsid, andoccasionally a membraneous envelope. The nucleic acid core is composed of all deoxyribonucleic acid or in the case of retroviruses, RNA, but never both. In retroviruses,the RNA gets transcribed to DNA bye the enzyme reverse transcriptase. Theprotein capsid is a protein forge that wraps around the virus. There are fourbasic shapes of viruses. The tobacco mosiac, adenovirus, grippe virus, andt-even bacteriophage are each examples of a different virus structure. Each unmarried protein subunit composing the capsid is a capsomere.The tobacco mosiac virus has a helical capsoid and is rod shaped. Theadenovirus is polyhedral and has a protein spike at each vertex. The influenzavirus is made of a flexible, helecal capsid. It has an outer membranousenevelope that is covered with glycoprotein spikes. The T-even bacteriophageconsists of a polyhedral head and a tail. The tail is used to inject DNA into abacterium while the head stores the DNA.Basic life is defined as the simplest form capable of displaying themost essential attributes of a living thing. This makes the however real criterionfor life the ability to replicate. Only systems containing nucleic acids arecapable of this phenomenon. With this reasoning, a better definition is theunit element of a continuous phone line with an individual evol utionary history.Because of viruses inability to survive when not in a host, they must haveevolved from other forms of life. The origin of viruses is an easy thing totheorize about(predicate) so many hypothesese have been made.One such hypothesis is that viruses were once complete living parasites.Over time they have lost all other cellular components. This is backed up bythe idea that all cells degenerate over time.Some people think along very similar lines that viruses arerepresentatives of an early "nearly living" stage of life. This goes along withthe first hypothesis in that it accounts for a loss of components. Allcreatures that become parasitic can be seen losing their obsolete functions and