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50 Cards in this Set
- Front
- Back
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Where is the term virus from? |
Latin for poison and slimy liquid |
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By how much do viruses outnumber cellular life? |
10:1 |
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How many bacteriophage particles in the ocean? |
10^31 |
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What % of human genome is from viral sequences |
8% |
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What is CThTV and how does it help plants? |
Colonizes a fungus that grows on plants, gives the plant thermotolerance |
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What is an enteric virus and give an example of how its helpful |
Replaces the beneficial relationship of commensal bacterial, for example restores the thin microvilli that appear in germ free mice |
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What are two important things viruses offer insight to in cell biology? |
1. Reverse Transcriptase 2. Identification of oncogenes - understanding that cancer is caused by mutation in these genes |
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What is a virus? |
An infectious, obligate, intracellular parasite |
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What do virus particles contain? |
A protein coat, genetic material, and sometimes and envelope derived from the host cel membrane |
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Two examples of large bacteria and their apparent size? |
1. Mimivirus (400nm) 2. Pandoravirus (1000nm) |
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Where did viruses come from? (3 postulates) |
1. Progressive hypothesis (from genetic elements) 2. Regressive hypothesis (remnants of cellular organisms) 3. Virus-first hypothesis (Predate or co-evolved with current hosts) |
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Who discovered the first virus, what was the type and how was it discovered? |
Dimitri Ivanoski- discovered tobacco mosaic virus passed through 0.2micron porcelain filters that retained bacteria |
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How do viruses replicate? |
Assembly of preformed components into many particles, after eclipse period, you have a burst of yield |
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What are the two phases that viruses exist in? |
The virion (inanimate) and the infected cell phase (multiplying) |
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What are the only 4 classes of hierarchy that viruses occupy? |
Order (virales), family (viridae), genus (virus), and species. |
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Define susceptible, resistant, and permissive cell |
Susceptible: has functional receptors for a virus Resistant: No receptors Permissive: competent capacity to replicate the virus |
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How do bacteriophages, plant, and animal viruses differ in terms of entry and uncoating? |
Bacteriophages have a special tail that drills holes in the cell wall and then injects genetic material, while plant viruses penetrate by damaging the cell wall, animal viruses do so by membrane fusion and endocytosis. |
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What do late viral genes usually express? |
Structural proteins used to make the viral particle coat |
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How do viruses with envelopes create their envelope? |
They encode glycoporteins that insert into lipid membranes and direct formation of the viral envelope |
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Based on the baltimore classification system how many types of viral genomes exist? What is the common point between them all? |
7, the common point is how they lead to mRNA |
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what is +mRNA, what does the (-) mean? |
The plus means it is the mRNA readily read by the ribosome. RNA/DNA complements of + are the negative (-) strands |
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What information is NOT found in viral genomes? |
Complete protein coding machinery, metabolism, centromere and telomere structures |
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What is the size of the largest known viral genome and who does it belong to? |
Pandoravirus with 2.5M nucleotides. other examples include megavirues, mamavirus, and mimivirus |
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What is the smallest known virus and what is its size? |
circovirus with 1800 nucleotides |
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What is the genetic system based on for BS class 1 genomes? |
dsDNA (+/-) |
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For BSC1 genomes, give an example of viruses whose 1. genomes are copied by the host DNA polymerases and 2. encode their own DNA polymerases |
1. Polyomaviridae/Pappilomaviridae 2. Adenoviridae/Poxviridae |
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What is BSC2 genomes made of, and any examples? |
ssDNA - need to convert to dsDNA when to mRNA then protein, circoviridae (circular) and parvoviridae (linear) |
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What is typical of RNA genome carrying virueses |
They encode Rdrp - produce mRNA from the RNA templates |
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BSC3 Genomes? What must these viruses carry? |
dsRNA - These viruses must carry Rdrp in the viral particle to convert dsRNA into mRNA§ |
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BSC4 Genomes? |
+ssRNA so can be directly translated hence don't need RdRp. |
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Examples of BSC4 viruses? |
Picornaviridae, Flaviridae, Coronaviridae. |
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BSC5 Viruses? |
-ssRNA, need Rdrp to convert to mRNA |
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BSC5 Examples? |
Orthomyxoviridae, Paramyxoviriae |
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BSC6? What do these do? |
+ssRNAT-RT. They have their own RT and turn their ssRNA into -ssDNA and the dsDNA, which is then inserted into the host gene |
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Which viral family is under the class 6 viruses? |
Retrovirus like HIV and HTLV |
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type of genome for BSC7? Give an example too |
dsRNA-RT: partially double stranded DNA that needs to be transcribed into dsDNA first, and then transcribed into useful mRNA An example is Hepadnaviridae (Hep B virus) |
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What are ambisense ssRNA genomes? |
The are genomes that, on a single strand contain both + and - ssRNA. They are not ribosome readable and need Rdrp to convert each section (genome or antigenome) into useable mRNA |
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What is the size of poliovirus, herpesvirus, and pandoravirus? |
30, 200, and 1000 nm |
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What makes viruses spring loaded? |
Energy that is put into the virus assembly is used as potential energy to disassemble the virus afterwards. Hence, it is "springloaded" with that energy |
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What keeps the viral coat stable? |
Symmetrical arrangement of identical proteins |
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The 4 tools used in assessing viral structure are? |
Electron Microscopy, X ray crystallography, Electron cryomicroscopy, NMR spectroscopy |
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In EM, what are some electron dense staining materials used and what is the overall resolution of the images? |
Uranyl Acetate/Phosphotungstate, and you will get a resolution of about 50-75A |
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IN CRYO EM, you freeze the particles and build a 3D reconstruction of the virus, what resolution do you get? |
you get a resolution of 8A |
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What is the resolution of X-Ray crys? And what organisms have been resolved through it? |
2-3A, TBSV and Poliovirus in 1985 |
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In the symmetry of viral particles, what type of symmetry do rod shaped and round viruses show? |
rod shaped: helical symmetry round: platonic polyhedra symmetry |
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What are the two rules for self assembly? |
1. Each subunit has identical binding contacts 2. Binding contacts are non-covalent, and reversible |
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What are VLPs |
Virus Like Particles, assebly of capsid proteins but no virus genome inside, purely just protein |
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What is an icosahedron? |
Solid with 20 faces, each an equilateral triangle |
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what is quasiequivalence |
When capsid contains more that 60 subunits, each occupies a quasiequivalent position |
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What are two exceptions to the symmetry rule for viruses? |
Poxvirus and pandoravirus |
