Term
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Definition
| obligate intracellular parasites; ultramicroscopic; infectious particles; protein shell around a nucleic acid; surface molecules dictate specificity |
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Term
| methods of visualizing viruses |
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Definition
| by electron microscope, through negative staining, positive staining, and shadowcasting |
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Term
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Definition
| allows visualization of the outline of a virus and its surface structure |
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Term
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Definition
| allows visualization of internal structure of viruses |
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Term
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Definition
| particles of metal are used to cover the virus in order to enhance the shape and surface features |
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Term
| primary features of a virus |
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Definition
| capsid, envelope, nucelic acid, may conatin some episodes |
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Term
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Definition
| present in all viruses; protein shell |
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Term
| functions of viral capsid |
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Definition
| protect nucleic acid; recognize host cells; recognition by the immune system |
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Term
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Definition
| identical subunits that combine to form the capsid |
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Term
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Definition
| rod-shaped capsomers assembled into a helix; those without an envelope have tightly wound, rigid capsid, and those that do have an envelope have a loosely wound, flexible capsid; ex. influenza, measles, rabies |
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Term
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Definition
| capsid is a 3D, 20 sided figure with 12 evenly spaced corners; number of capsomers vary; overall shape can vary depending on the shape of the individual capsomers |
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Term
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Definition
| present in most animal viruses, but not bacterial viruses; covering that surrounds the capsid; usually made from a modified section of the host cell's membrane |
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Term
| functions of viral envelope |
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Definition
| protect nucleic acid, recognize host cells, recognition by the immune system |
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Term
| composition of viral envelope |
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Definition
| host proteins are replaced with viral proteins; proteins connect the envelope to the capsid; glycoproteins protrude from the envelope to form spikes which serve to recognize and attach the virus to the host cell |
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Term
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Definition
| very short; do not carry genes for metabolism; most contains dsDNA or ssRNA; may be linear or circular; RNA viruses may be positive or negative sense |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| no offical scientific names; based on strcuture, chemical composition, and genetic make-up; relies heavily on the sub-category of strains |
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Term
| steps in replication of animal viruses |
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Definition
| absorbtion, penetration, uncoating, synthesis, assembly, release |
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Term
| absorbtion in animal viruses |
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Definition
| virus recognizes and attaches to host cell via receptor proteins on the cell membrane; the host range is determined by the type of cell receptor proteins a virus recognizes |
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Term
| penetration of animal viruses |
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Definition
| by either endocytosis or fusion |
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Term
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Definition
| entire virus is engulfed by the cell |
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Term
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Definition
| viral envelope fuses with the cell membrane, then releases the nucelocapsid into the cell |
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Term
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Definition
| if the viral particle is inside a vesicle, enzymes will dissolve the envelope and capsid; if the viral particle is free in the cytoplasm, enzymes in the cytoplasm will dissolve the capsid |
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Term
| synthesis in animal viruses |
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Definition
| DNA will move to the nucleus where it is transcribed by the host's machinery; RNA will usually be replicated in the cytoplasm; proteins for the capsid, spikes, and viral enzymes are synthesized on the host's ribosomes using the host's amino acids |
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Term
| assembly in animal viruses |
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Definition
| capsids are constructed as an empty shell into which nucleic acid is inserted; spikes are inserted into the host's membrane where they can be picked up by the virus upon exit |
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Term
| release in animal viruses |
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Definition
| nonenveloped viruses are released when the host cell lyses (ruptures); enveloped viruses exit by exocytosis |
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Term
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Definition
| completely assembled virus particle ready for release |
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Term
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Definition
| virus-induced damage to a cell that alters its microscopic appearance; may include swelling and/or the development of inclusion bodies |
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Term
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Definition
| multiple host cells combine into a single cell with multiple nuclei |
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Term
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Definition
| virus is carried within a host cell for extended periods of time; will cause progressive damage to the cell, but will not kill the cell |
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Term
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Definition
| virus remains inside the host cell in an inactive state for an extended period of time; may become reactivated; ex. chicken pox, epstein-barr virus |
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Term
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Definition
| insert into the host's DNA in a manner that promotes development of cancer; ex. epstein-barr, burkitt's lymphoma, HPV, cervical cancer |
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Term
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Definition
| bacteriophages; make bacteria more pathogenic; no envelope; if viral genome inserts into bacterila genome prior to replication, can promote genetic diversity |
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Term
| steps in bacteriophage replication |
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Definition
| absorbtion, penetration, replication, assembly, release, and sometimes lysogeny |
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Term
| absorbtion in bacteriophage replication |
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Definition
| similar to animal viruses |
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Term
| penetration in bacteriophage replication |
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Definition
| entire phage does not penetrate; nucleic acid is inserted into the cell; capsid remains outside the cell; uncoating step is not necessary |
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Term
| replication and assembly in bacteriophage replication |
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Definition
| similar to animal viruses |
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Term
| release in bacteriophage replication |
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Definition
| only occurs through cell lysis; aided by viral enzymes that help to digest the cell envelope |
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Term
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Definition
| stage present in some bacteriophage replication cycles; viral DNA is inserted into the host's DNA prior to replication; viral DNA remains inactive for a period of time; viral DNA is replicated with host DNA and passed on to daughter cells; allows virus to spread without killing the cell; makes host more pathogenic because inactive viral DNA often encodes a toxin (diptheria, cholera, botulism) |
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Term
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Definition
| studying viruses in animals |
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Term
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Definition
| studying viruses in a cell culture |
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Term
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Definition
| smaller than viruses; contain protein but no nucleic acid; ex. mad cow disease |
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Term
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Definition
| virus-like agents; smaller than viruses; infect plants; composed only of RNA (no capsid or envelope) |
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