Viruses: They are tiny, non-living particles that rely on host cells to replicate. They are the smallest of the microbes and range from 0.02-1.25microns. They consist of a core genetic material, either DNA or RNA, surrounded by a protective protein coat called a capsid. Some viruses have spikes that allow it to grab onto it's host cell. To replicate a virus must invade a host cell and hijack it's cellular machinery. The virus's genetic material is injected into the host cell, where it instructs the cell to produce new viral particles. Once the new viruses are assembled, they are released from the host cell, often destroying it in the process.
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