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47 Cards in this Set
- Front
- Back
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What are viruses?
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obligatory intracellular parasites
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What are the different components of viruses?
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contain DNA OR RNA, protein coat, some have an envelope surrounding the coat, some have spikes, MUST infect only specif types of cells in one host, the host range is determined by specific host attachments and cellular factors
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Do viruses contain DNA, RNA, or both?
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DNA or RNA (one or the other)
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What is the host range of viruses?
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The range of the cells a particular virus will attack
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What is the host range of a virus dependent on?
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specific host attachment sites and other cellular factors
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Do all viruses have a protein coat?
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Yes
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Do all viruses have an envelope surrounding the protein coat?
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no, some do some don't
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Do all viruses have spikes?
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no, some do some don't
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What are viral species?
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a group of viruses sharing the same genetic information and ecological niche
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What are plaques?
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bacteriophages form plaques on a lawn of bacteria (congregates of cell death)
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How are viruses identified?
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cytopathic effects, serological effects, and by the nucleic acid tests
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What are serological effects?
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A way to identify viruses. To see if the body is making an antibody for the specific virus. Includes neutralization tests, viral hemagglutinzation and the western Blot.
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What are lytic viruses?
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lysis= cell deaht. Viruses that kill the host cell by causing lysis.
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What are the different stages of lytic cycles?
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attachment, penetration, biosynthesis, maturation and release
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Describe the attachment stage of a lytic cycle.
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The phage attaches by tail fibers to the host cell.
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Describe the penetration stage of the lytic cycle.
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The phage lysozyme opens the cell wall; tail sheath contracts to force tail core and DNA into the cell.
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Describe the biosynthesis stage of the lytic cycle.
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Production of phage DNA and proteins
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Describe the maturation stage of the lytic cycle.
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Assembly of phage particles.
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Describe the release stage of the lytic cycle.
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Phage lysozyme breaks the cell wall.
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What are lysogenic phages?
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phage DNA is incorporated into the host DNA. any time the cell divides, the phage divides to.
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How do lytic and lysogenic phages differ?
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lysogenic can become lytic. lytic cannot become lysogenic. lysogenic eventually becomes lytic.
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What is generalized transduction?
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transferring DNA from bacteria/host to the virus cell. It is a RANDOM piece of DNA....accidentally some virus DNA gets incorporated into the host.
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What is specific transduction?
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taking a specific portion of DNA from the host cell. It is a special part of the DNA that is transferred from the host to the virus cell.
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What are the steps in an animal viral cycle?
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attachment, penetration, uncoating, biosynthesis, maturation, release by budding OR rupture
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How are lytic cycles different from animal viral cycles?
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animal viral cycles have an "uncoating" step and the penetration step is different; in animals the entire virus goes in not just the genetic information.
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How do animal viruses enter the cells?
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via pinocytosis or fusion
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How do enveloped animal viruses bud?
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steals membrane from the host
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Explain the attachment step of the animal viral cycle
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viruses attach to the cell membrane
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explain the penetration step of an animal's viral cycle
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entire virus goes in via endocytosis or fusion
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explain the uncoating step of an animal's viral cycle
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The DNA or RNA of host is cut
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explain the biosynthesis step of an animal's viral cycle
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production of nucleic acid and proteins
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explain the maturation step of an animal's viral cycle
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nucleic acid and capsid proteins assemble
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explain the release step of an animal's viral cycle
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release is by budding if enveloped, if not then ruptures
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What are transformed cells?
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activated oncogenes transform normal cells into cancerous cells. These transformed cells have increased growth, loss of contact inhibition.
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What are oncogenic viruses?
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The genetic material of oncogenic viruses becomes integrated into host cells.
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What is the difference between oncogenic viruses and transformed cells?
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Oncogenic viruses may cause the occurence of transformed cells. Oncogenic viruses are thus named because the genetic material of cancer causing viruses becomes integrated into host cells. These host cells are transformed cells.
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What are latent viral infectoins?
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When a virus remains asymptomatic in the host cell for long periods of time.
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What are persistent viral infectoins?
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disease processes occur over a long period of time; generally it is fatal.
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What are the difference between latent and persistent viral infections?
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in latent viral infections, the host cell remains asymtomatic for long periods of time. In persistent viral infections, the symptoms show up slowly over the course of a long period of time.
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What are prions?
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They change the normal protein! Prions are proteins that can infect! They are inherited and transmissile by ingenstion, transplant and surgical instruments.
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True or false: Viruses are the smallest material that can kill you.
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False: prions are smaller than viruses!
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How are prions transmitted?
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inherited, ingested, on non-sterile transplant/surgical instruments
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What is PrPc?
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An example of a normal cellular prion protein located on a cell's surface.
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What is PrPsc?
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A scrapie protein; accumulates in brain cells, forms plaques.
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How do plant viruses enter?
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through wounds or via insects
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What are viroids?
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normally found in plants, not animals. Small pieces of RNA that are infectious.
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What term best describes the statement:
"Small pieces of RNA that are infectious." |
viroids
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