1. Biology
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2. Viruses
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3. What Is a Virus? Viruses are particles of nucleic acid (DNA or RNA), protein, and in some cases, lipids. Viruses can reproduce only by infecting living cells (hosts).
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Viruses come in a wide variety of sizes and shapes. A typical virus is composed of a core of either DNA or RNA, which is surrounded by a protein coat, or capsid.
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Control, England/Photo Researchers, Inc.

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6. What Is a Virus?
A typical virus is composed of a core of DNA or RNA surrounded by a protein coat. A capsid is the virus’s protein coat.
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7. Some viruses replicate immediately, killing the host cell.
Viral Infection
Once the virus is inside the host cell, two different processes may occur.
Some viruses replicate immediately, killing the host cell.
Others replicate, but do not kill the host cell immediately.
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Viral Infection
Bacteriophage injects DNA into bacterium
Bacteriophage DNA forms a circle
Lytic Infection
Lysogenic Infection
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
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9. Lytic Infection
In a lytic infection, a virus enters a cell, makes copies of itself, and causes the cell to burst.
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10. Viral Infection Copyright Pearson Prentice Hall
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.

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Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.

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Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.

13. Lysogenic Infection Other viruses cause lysogenic infections in which a host cell makes copies of the virus indefinitely. In a lysogenic infection, a virus integrates its DNA into the DNA of the host cell, and the viral genetic information replicates along with the host cell's DNA.
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Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.

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Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.

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Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.

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Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.

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19. Retroviruses contain RNA as their genetic information
Retroviruses contain RNA as their genetic information. When retroviruses infect cells, they make a DNA copy of their RNA. This DNA is inserted into the DNA of the host cell.
Retroviruses
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21. Works on Bacteria- Antibiotic: Chemical produced by a microorganism that kills or inhibits the growth of another microorganism

22. Specific antivirals are used for specific viruses.
Antiviral drugs are a class of medication used specifically for treating viral infections.
Specific antivirals are used for specific viruses.
Antiviral drugs do not destroy their target pathogen; instead they inhibit their development.