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Biology Copyright Pearson Prentice Hall
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Viruses Copyright Pearson Prentice Hall
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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). Copyright Pearson Prentice Hall
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Copyright Pearson Prentice Hall
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. Photo Credits: l. ©M.Wurtz/Biozentrum, University of Basel/Science Photo Library/Photo Researchers, Inc. m. ©Dr. O. Bradfute/Peter Arnold, Inc. r. ©National Institute for Biological Standards and Control, England/Photo Researchers, Inc.
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Copyright Pearson Prentice Hall
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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. Copyright Pearson Prentice Hall
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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. Copyright Pearson Prentice Hall
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Copyright Pearson Prentice Hall
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. Copyright Pearson Prentice Hall
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Lytic Infection In a lytic infection, a virus enters a cell, makes copies of itself, and causes the cell to burst. Copyright Pearson Prentice Hall
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Viral Infection Copyright Pearson Prentice Hall
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
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Copyright Pearson Prentice Hall
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
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Copyright Pearson Prentice Hall
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
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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. Copyright Pearson Prentice Hall
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Copyright Pearson Prentice Hall
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
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Copyright Pearson Prentice Hall
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
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Copyright Pearson Prentice Hall
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
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Copyright Pearson Prentice Hall
Bacteriophage may infect cells in two ways: lytic infection and lysogenic infection.
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Copyright Pearson Prentice Hall
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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 Copyright Pearson Prentice Hall
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Works on Bacteria- Antibiotic: Chemical produced by a microorganism that kills or inhibits the growth of another microorganism
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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.
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