Beginning of Essay
? Viruses have been defined as "entities whose genomes are elements of nucleic acid that replicate inside living cells using the cellular synthetic machinery, and cause the synthesis of specialised elements that can transfer the genome to other cells." They are s ....

Middle of Essay
.... bacteriophage are each examples of a different virus structure. Each individual protein subunit composing the capsid is a capsomere. The tobacco mosiac virus has a helical capsoid and is rod shaped. The adenovirus is polyhedral and has a protein spike at each vertex. The influenza virus is made of a flexible, helecal capsid. It has an outer membranous enevelope that is covered with glycoprotein spikes. The T-even bacteriophage consists of a polyhedral head and a tail. The tail is used to inject DNA into a bacterium while the head stores the DNA. Basic life is defined as the simplest form capable of displaying the most essential ....