Ch.16 and 31

Ch.16 and 31 - Virus Structure and Reproduction short piece...

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Virus Structure and Reproduction short piece of nucleic acid, DNA or RNA, surrounded by a protein coat. Some viruses also have outer membranes that merge with a host cell's membrane, making it easier for the virus to infect the cell. Since a virus doesn't have its own cellular machinery, it must use the host cell's machinery to make copies of itself. Viruses and Disease phospholipid membrane with projecting spikes of protein. The envelope helps the virus enter and leave a cell. RNA rather than DNA as their genetic material. A disease-causing virus uses the equipment of the host cell to reproduce. Therefore, the approaches to control and cure viral infections are different from bacterial infection controls. HIV: A Retrovirus The disease called AIDS (Acquired Immune Deficiency Syndrome. HIV (Human Immunodeficiency Virus) is the name of the specific virus that results in AIDS. HIV has a membranous envelope that helps the virus recognize host cells and merge with its membrane, delivering its contents to the host cell. Retroviruses are so named because they reverse the usual DNA-to-RNA flow of genetic information in the process called reverse transcription. Retroviruses carry an enzyme called reverse transcriptase When the virus remains inactive in the host cell DNA, the disease symptoms are not evident. Only when the virus reproduces and destroys host cells does the immune system become damaged, and the individual becomes ill with AIDS.
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Defense Against Viral Diseases Vaccines are deactivated varieties or small pieces of pathogens that stimulate the immune system to defend against the actual pathogen. The first vaccine was made against the virus that causes smallpox in the late 1700s, Edward Jenner, an English physician, learned that milkmaids who had contracted were resistant to later infections of smallpox Some viruses, including the common cold virus and HIV, mutate rapidly. The resulting new strains are not recognized by a previously vaccinated immune system. This means that vaccines could not protect you from every existing strain and could quickly become outdated. Medical technology can do little, at present, to cure most viral infections. However, a few drugs have been developed that do combat viruses, primarily by interfering with their nucleic acid synthesis or with the action of reverse transcriptase. How Bacteria Cause Illness Bacteria and other microorganisms that cause disease are called pathogens . Even some of the bacteria that are normal residents of the body can make you sick when you are weakened by lack of sleep, poor nutrition, or another disease. inhaled or transmitted by touching. sexual contact, bite of a tick, improperly stored or prepared foods
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Ch.16 and 31 - Virus Structure and Reproduction short piece...

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