Bacteria And Viruses Essay

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Describe the structure and function of bacteria in comparison to a virus

Both bacteria and viruses are mircoogranmisms. Viruses are small obligate intracellular parasites, which by definition contain either a RNA or DNA genome surrounded by a protective, virus-coded protein coat called a caspid. They are classed as non-living because they cannot surive on their own. Conversley, bacteria are single celled livng microbes. The cell structure is simpler than that of other organisms as there is no nucleus or membrane bound organelles, but much more complex than a virus. Instead their control centre containing the genetic information is contained in a single loop of DNA. Some bacteria have an extra circle of genetic material called a plasmid.
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Nucleic Acid Contains genetic material, which may be double or single stranded DNA or RNA. This allows for the synthesis of viral proteins.
Tail Fibres Allow the virus to attach to host cell and move.
Lipid Envelope (Dervied from host cell membrane) Fuses with the host's membrane, allowing the capside and viral genome to enter and infect the host.
Repeating protein unit, which makes up the protein coat.

In order for a virus to infect a cell, it must bring its DNA or RNA into contact with the host cell. Therefore, infection requires that the virus get through the cellular membrane. Some viruses remain outside the cell. They attach to the membrane at specific receptor sites and or antigen sites called VAPs (Virius Attachment Particles). Once attached the virus injects its DNA or RNA into the cell [3]. Enveloped viruses are enclosed in a membrane similar to that of the host cell. The virus and the envelope fuse and the virus enter the cell through endocytosis. Viruses are not restriced to humans only. Many viruses can also infect other orgranims and microogranism. Such a virus is a

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