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37 Cards in this Set
- Front
- Back
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Where do plant viruses bind?
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Plant viruses do NOT bind to surface receptors
Infection of plant cells requires cell wounding |
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Horizontal Transfer
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Occurs from plant to plant (within generations) such as when plants are touching each other
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Vertical Transfer
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Occurs from parent to offspring such as infected seeds (between generations)
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What kind of transmission happens between plants and plant viruses?
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Plants may be physically damaged by wind
Viruses in the soil can enter the plant. Soil acts as an abrasive, causing damage that will give the virus access to plant cells |
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How does grafting cause infection?
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An infected scion is grafted onto a healthy rootstock
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In grafting, what are the plant components involved?
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Scion
Cambium (interface between both) Stock |
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Which organisms act as vectors to spread plant viruses?
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Bacteria
Fungi Nematodes Parasitic plants Insects |
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Symptoms of plant diseases
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Dwarfing or stunting of plants
Leaf curling Reduced yield Fruit distortion Chlorosis (yellowing) Other color deviations (e.g. variegation of flower petals) “mosaic” patterns on leaves Ring-spots on leaves Wilting and withering Necrosis Bark scaling |
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What are the methods for "Diagnosis and Detection of Plant Viruses"
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Direct detection of particles by electron microscopy
Inclusion bodies in infected cells by light microscopy Infectivity assays Serology (ELISAs) DNA or RNA probes (e.g. PCR) |
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Which plant viruses contain envelopes?
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Rhabdo and tospo
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What is the morphology of plant viruses?
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Most plant viruses are naked helical roots
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What are the 3 types of rods of plant viruses?
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Long, helical
Rigid helical Short rods |
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which DNA is the rarest type of plant virus genome?
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dsDNA
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What are the majority of plant virus genomes?
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+ssRNA, dsRNA, and ssDNA
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What differs between plant and animal viruses?
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Multipartite Plant Viruses Package Each Nucleic Acid Molecule Into a Separate Virus Particle
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What is a disadvantage of multipartite genomes of plant viruses?
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All the particles must be taken up into a single cell in order to establish infection
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how do viruses enter a cell, or move from one plant cell to the next?
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Plants contain an impermeable cell wall
Viruses enter through a break in the cell wall or channels called plasmodesmata Viruses have evolved specialized movement proteins to allow them through the plasmodesmata from one infected cell to neighboring cells |
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How do systematic plant infections occur?
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If the virus can be distributed long distances by traveling through the vascular system (phloem)
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What are movement proteins / plasmodesmata complexes derived from?
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host plant genes coding for chapteronins
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Describe plant satellite viruses
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Satellite viruses encode their own coat protein but lack the genes that would encode the enzymes necessary for replication
Satellite viruses are completely dependent upon helper viruses for replication Satellite RNAs or DNAs become packaged in a protein capsid form the helper virus Genetic material is 200-1500 nucleotides in length (has little sequence similarity to the helper virus genome) |
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Does the satellite virus help the helper virus?
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No. Replication of the satellite virus interferes with replication of the helper virus
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What did rosalind franklin do?
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she hypothesized that TMV particle was hollow and that its RNA genome was single-stranded
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Purified TMV RNA is what proportion of what?
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Purified TMV RNA is 95% RNA and 5% coat protein
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what kind of genome does TMV have?
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+ssRNA
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describe the TMV ORF
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The first ORF codes for an RNA dependent RNA polymerase (RdRp) that has helicase and methyltransferase activity
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describe Plant Virus +ssRNA Genome Replication
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These viruses encode their own RNA-dependent RNA polymerases for genome replication
Utilize host factors for the formation of the replicase complex |
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What 3 genes do most plant viruses have?
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1 or more involved with the replication of the viral genome
1 or more concerned with cell-to-cell movement of the virus 1 or more encoding a structural protein that makes up the coat or capsid protein of the virus |
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Plant Virus Exiting
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Viruses exit through the modified plasmodesmata without causing cell lysis
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What is the naming rule for plants?
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Plant viruses as a general rule are named after the first plant on which they are found.
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what is the most studied plant virus?
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Tobacco Mosaic virus
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what are the characteristics of TMV RNAs
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The TMV viral RNA is infectious and acts like a mRnA that is translated by the host machinery
After RdRP is synthesized, it begins to replicate full-length -ssRNAs or 3 additional shorter -ssRNAs, called subgenomic RNAs, which function as monocistronic RNAs. |
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what are TMV subgenomic RNAs?
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They are monocistronic RNAs
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why is it hard to prevent TMV infection in nature?
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because of the stability of the virus
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how long of a feeding does it take for an aphid to become infectious with CTV?
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10 minutes
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What is the largest known plant virus?
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CTV
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How many protein products does CTV have?
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17
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What is the main component of anti-crop research?
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fungal and bacterial pathogens
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