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37 Cards in this Set
- Front
- Back
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How does the virus get into host cell? |
Infection: injects genetic info into host cell to manufacture viruses and promote infection |
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How are viruses different in comparison to cells? |
-Thy are much smaller, much simpler. -an infectious particle of DNA (genes) in a protein coat -non-living. |
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What do viruses consist of? |
nucleic acid surrounded by a protein coat |
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what size are viruses usulally measured in |
Nano, 10^-9, 0.000000001 |
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What is the structure of viruses |
nucleic acid, double strand or single strand, linear or circular. 3-1000 genes, surrounded by a protein coat (capsid) |
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Helical virus are what shape? |
rod shaped. ex: tovacco mosaic virus |
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Icosahedral virus are what shape? |
polyhedral shaped. ex: adenoviruses |
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example of a viral envelope (from host cell) shaped cell |
influenza viruses |
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example of icosahedral virus with tail and fibers |
bacteriophage T4 |
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where do viruses replicate? |
in host cell |
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Do viruses have ribosomes? |
No |
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What are the phases of viral replication? |
1. virus attaches to cell, 2. virus penetrates cell membrane and injects nucleic acid into cell, 3. viral nucleic acid replicates using host cellular machinery, 4. new viral nucleic acids are packaged into viral particles and released from the cell. the host cell may be destroyed in the process. |
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Lytic Cycle: |
Bacterium death at last stage of infection. Lysing (breaking open) of host cell to release virus |
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how to virulent phages replicate? |
lytic cycle |
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lysogenic cycle |
host not destroyed (host and virus coexist in lysogeny) called a prophage. |
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temperate phages: |
use lytic and lysogenic cycles, determined by environmental pressures. ex: 0157:h7 and E.coli |
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Examples of viruses that contain phage toxins |
diptheria, botulism and scarlet fever |
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Why haven't viruses caused bacterial extinction? |
lysogeny (coexist). natural selection favors surface proteins on bacteria that are not recognized receptors. restriction enzymes cut up phage DNA (restricts viral replication), and CRISPER Cas System. |
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CRISPR-Cas System acronym stands for what? |
clustered regularly interspaced short palindromic repeats |
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Describe CRISPR-Cas System. |
CRISPR isone part of the bacteria’s immune system, which keeps bits of dangerous virusesaround so it can recognize and defend against those viruses next time theyattack. •Thesecond part of the defense mechanism is a set of enzymes called Cas (CRISPR-associatedproteins), which can precisely snip DNA and slice invading viruses. •Conveniently,the genes that encode for Cas are always sitting somewhere near theCRISPR sequences. |
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what are the key factors for infection and replicatino |
whether the genome is double or single stranded RNA/DNA. and the presence or absence of an envelope. (viruses use membrane of host cell to build its envelope and fuse into the cell or enter by endocytosis and leave by exocytosis.) |
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What type of virus is HIV |
an RNA retrovirus |
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Describe RNA Retrovirus |
"backward" (RNA ->DNA flow), reverse transcriptase, viral DNA enters nucleus, integrated viral DNA is a "provirus", permanently integrated. |
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What is Reverse Transcriptase |
Transcribes RNA template into DNA |
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What are pandoravirus and Mimi virus? |
Pandoravirus is a really large type of virus. |
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what are formidable pathogens in animals and plants? |
viruses and prions |
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is the infected tissue able to regenerate? nerve tissue, epithelial tissue? |
polio (nerve tissue) - no. epithelial tissue - yes. fever and body aches are caused by bodys response to virus, not virus directly |
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Define vaccine: |
preventitive; derivative of pathogen that stimulates immune system to build antibodies |
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examples of types of viruses |
colds, flu, most coughs and bronchitis, sore throats, some ear infections |
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examples of some bacteria |
strep, urinary tract infection, most ear infections, some sinus infections, bacterial pinkeye |
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What is HOST RANGE: |
number of host species that a particular virus can infect. often times infection is limited to specific tissues |
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What is the host range of measles? |
Small host range: very contagious, easily spread illness caused by a virus through respiration. causes fever red rash on skin, mostly occurring in childhood |
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what is the host range of small pox |
small host range, only humans |
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what does pandemic mean |
global |
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describe emerging viruses |
mutation, dissemination from isolated source, cross-specie transfer. annual flu, ebola: hemorrhagic fever, west nile virus: encephalitis, H1N1: influenza (swine flu) |
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What are Prions? |
Mis-folded brain proteins, results in degenerative brain, ex: mad cow disease and creutzfeldt-jakob |
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viral eradication |
when they get rid of a virus all together.ex : smallpox |
