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amanda430
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What is a virion?
nucelic acid surrounded by a protein coat
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What is a capsid?
the protein coat
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What is a nucleocapsid?
A capsid with enclosed nucleic acid
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What is an enveloped virus?
A virus with a lipid bilayer outside of the capsid
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What is a naked virus?
- A virus that is not enveloped
- Most phages
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What are the 3 different shapes of viruses?
- Icosahedral
- Helical
- Complex
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What does an Icosahedral Virus look like?
20 flat triangles, resembles a soccer ball
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What does a helical virus look like?
Appears cylindrical, nucleic acid is in a helix
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What does complex virus look like?
Has a complicated structure
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What is an arboviruse?
- spread by arthropods
- ex mosquitos
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What is the Lytic phage infections model?
T4 phage
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What is a lytic/virulent phage?
- exits host at end of infection cycle via lysing
- a productive infection
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What are the 5 steps of a T4 (lytic/virulent) infection cycle?
- Attachment
- Genome Entry
- Synthesis of Phage proteins and genome
- Assembly
- Release
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What occurs during the T4 attachment phase?
- phage collides with host cell by chance
- attaches to a receptor/pilus on cell that would normally be used for other functions
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What occurs during the T4 genome entry phase?
- post-attachment phage injects it's DNA/RNA into the cell via it's tail degrading a bit of the cell wall with lysozyme
- After nucleic acid is injected the capsid remains on the cell's surface
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What occurs during the T4 Synthesis of phage proteins and genome phase?
- T4 genes are transcribed and translated quickly
- Proteins are synthesized to hijack the cells processes
- Proteins are synthesized to create the phage parts
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What occurs during the T4 Assembly phase?
once all components are synthesized they are assembled into new phage particles with the help of scaffolds
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What occurs during the T4 release phase?
the phage encoded enzyme lysozyme is produced and degrades the cell wall from the inside out causing the cell to lyse
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What occurs during Temperate Phage infections?
The can be lytic or lysogenic
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What is the difference between a lytic infection and a lysogenic infection?
- lytic is a productie infection
- lysogenic is a latent infection
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What occurs during a lysogenic infection?
- phage's DNA becomes integrated into host's DNA
- host is called a prophage
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What are the consequences of lysogeny?
- immunity to superinfection
- lysogenic conversion
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What prevents gene excision in a prophage?
a repressor
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What is immunity to superinfection>
- The same phage cannot reinfect a prophage
- the repressor which maintains the lysogenic state will repress the incoming phage
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What is lysogenic conversion?
modification of host's properties resulting from expression of phage DNA integrated into the host
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What is an example of a temperate infection?
Lambda
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What is a filamentous phage?
- looks like long fibers
- causes productive infections that slow down reproduction
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What is an example of a filamentous phage?
M13
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What occurs during M13 filamentous infection?
attaches to F pilus and injects itself into cytoplasm where it is synthesized and replicated
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What is transduction?
the transfer of DNA via a phage
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