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Viruses: Characteristics, Reproduction, and Control

Learn about viruses, their DNA or RNA composition, shapes, sizes, specificity, and examples like influenza and AIDS. Explore lytic and lysogenic infections, retroviruses, and ways to control viruses using vaccines, interferon, and antibodies.

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Viruses: Characteristics, Reproduction, and Control

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  1. Virus Notes Chapter 19 Section 19-2

  2. Virus Characteristics • Viruses are particles of nucleic acid, protein, and lipids that invade living cells and reproduce. They are composed of a core of DNA or RNA surrounded by a protein coat called a capsid. • Examples of Viruses: Influenza, colds, chicken pox, measles, polio, and AIDS.

  3. Ways viruses vary……. • 1. Shape – they come in a variety of shapes. (see next slide) • 2. Size 20-400 nanometers. 1 nanometer = 1 billionth of a meter. • 3. Specificity = certain viruses only infect certain organisms…your dog can’t get chickenpox!

  4. Examples

  5. Retroviruses • Retroviruses: Contain RNA as their genetic information. It is then copied to DNA. This is “backwards” or “retro”. • Viruses are considered parasites because they must infect a living cell in order to grow and reproduce.

  6. Viral Reproduction #1 • 1. Lytic Infection – a virus enters a cell, makes copies of itself and causes the cell to burst • Attaches, entry, replication, assembly and release • http://www.npr.org/templates/story/story.php?storyId=114075029

  7. Viral Reproduction #2 • Lysogenic Infection – a virus integrates its DNA into the DNA of the host cell. It many remain inactive for a period of time. • The viral DNA is called a prophage.

  8. 3 Ways to control viruses: • 1. Vaccine – a weakened dose of the virus. When injected it usually prompts the body to produce an immune reaction to prevent illness.

  9. Ways to control viruses: • 2. Interferon – proteins that prevent virus from attaching to your cells and reproducing.

  10. Ways to control viruses: • 3. Antibodies – immune system proteins that attack and kill bacteria and viruses.

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