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Viruses
Viruses are tiny particles that invade living cells.
1. Viruses are not cells because they cannot perform the life functions of living cells.
2. Viruses require a host organism, or living cell, to reproduce.
3. Viruses are parasites because they harm living cells.
A virus has two basic parts:
1. a core of hereditary material
2. an outer coat of protein
Viral Host Cell Infection
1. After a cell attaches to its host cell, it injects its hereditary material into that cell.
2. After injection, the protein coat is left behind.
3. The injected genetic material begins to use the supplies in the host cell to
manufacture new viruses.
4. After a period of time, the host cell bursts open, releasing the new viruses which
seek out new cells to infect.
Infections caused by viruses include:
1. Annoying diseases such as colds, fever blisters and warts
2. More serious diseases such as AIDS, measles, influenza, hepatitis, smallpox,
polio, mumps and herpes
Scale and Structure of Viruses
1. Viruses are noncellular and consist of a core of hereditary material and an outer
coat of protein
2. The protein coat protects the virus and allows it to attach to a host
3. The genetic material allows the virus to reproduce after a host is injected