Are Viruses Considered To Be Living Organisms Essay

Are Viruses Considered To Be Living Organisms - Essay Example In 1876, even though the nature of virus was not recognized at the time, yet, it was anticipated that the number of species of virus are greater than that of all other living things put together. Viruses are parasites as they can’t nurture themselves and require a host cell for nutrition, growth and reproduction. All viruses are harmful; in fact their capability to operate as ‘mobile genes’ is considered to have inclined the hereditary make-up and development of higher living beings. Indeed their similarity to the genetic material of higher organisms that can move from one genetic material to another can be considered to be as evidence of their beginning. Nowadays, many experts consider that viruses have been descended from bacterial plasmids (small package of genes residing on the outer side of the chromosomes of bacteria and have the ability to transfer from one bacterium to another). Viruses are not similar to human or bacterial cells. They are tiny creatures t hat can’t be seen with a normal light microscope. Their size is said to be of only one-millionth part of an inch. Viruses may even infect bacteria to reproduce themselves; the Bacteriophage virus for example requires bacteria for the completion of its life cycle. Once infected, the host cell stops its functioning rather starts serving the viral requirements resulting in the onset of infection to the host (Holzenburg and Bogner, 2002). Viral Structure A virus mainly consists of three parts. 1. Capsid – It is a protein coat that environs the nucleic acid to protect it. 2. Nucleic acid – It is the basic genetic material; either RNA or DNA that grasps all the data for the virus and contrast each virus from another. 3. Envelope – It is a lipid membrane that envelops the capsid (protein coat). However, it is not present in all viruses. Those viruses that possess envelop are said to be enveloped viruses while those that lack it are called naked viruses. Fig1. Ch aracteristic Viral Structure Lytic cycle The lytic cycle which represents the life cycle of virus involves six basic steps 1. Adsorption as the virus gets attached to the host cell. 2. Entry: The attached virus then penetrates the cell by injecting its genetic instructions (RNA or DNA) into the cytoplasm of the host cell. 3. Transcription: The injected viral genetic material takes control of the host cell’s nucleus and starts directing the enzymes of the host. 4. Replication: Fragments of new viruses are made using particular enzymes. 5. Assembly: The fragments formed are then assembled to form new viruses. 6. Release: The novel viruses destroy the host cell and burst out to attack new host cells and continue this cycle. Virus Non Living or Living? Viruses are usually kept on the borderline between living and non living beings. Some features of viruses make them considered as living beings while other lead to the development of opinion of considering them as non living. Virus es are regarded as living on the basis of their proposed evolution via natural selection and ability to reproduce themselves. Viruses can be regarded non living as they are acellular and require a host to perform its metabolic and reproductive activities. Viruses are convoluted assemblage of molecules, including nucleic acids, proteins, carbohydrates and lipids, but unable to do anything on their own until they penetrate the host cell. The