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33 Cards in this Set
- Front
- Back
The land of the super tiny! From 3-200 genes; Obligate intracellular parasites; Known from ancient times |
Viruses |
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General Characteristics |
Not Cells obligate intracellular parasites small.. 20nm - 350nm Single type of nucleic acid Protective Coat Specific "Host Range" |
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Virus Structure Capsids, Nucleic Acid, Envelope |
Icosahedral, Helical |
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What is a Capsid? |
protein coat that surrounds the nucleic acid protects genome recognizes/binds host stimulate immune system made of viral capsid protein (capsomeres) |
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What are Capsomeres? |
subunits of the protein coat |
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What is the symmetry of Icosahedral? |
12 corners 20 faces 30 edges VERY STABLE **NUCLEIC ACID usually not ordered inside |
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Describe the envelope... |
Made of host membrane recognizes/binds to host protects capsid |
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Internal properties |
RNA or DNA (not both) * only viruses among all of life can have RNA as a genome Single stranded or double stranded **only viruses among all of life can have single stranded genomes One piece or multiple Linear or circular As few as 3 genes, as many as 250 |
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Structure of an Influenza virus... |
Envelope Spkies Helical nucleoprotein has ssRNA in 8 segments |
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What are bacteriophages? |
Viruses of bacteria |
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Bacteriophage viral multiplication... |
RAPI-BAR Recognition Attachment Penetration Insertion Biosynthesis Assembly Release |
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Animal viral multiplication... |
RAPI-UBAR Recognition Attachment Penetration Endocytosis or fusion Stimulated by attachment Uncoating: capsid unchaste away from nucleic acid How the DNA/RNA gets out Biosynthesis Assembly Release |
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Explain Endocytosis.. |
Virus is "eaten" by cell- uptake in vacuole Exists in a membrane bound vesicle (from host) Must be uncoated in separate step EX: herpes virus |
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Explain Fusion... |
Virus coat blends into the plasma membrane of the host No vesicle Is uncoated in the same step as penetration EX: Mumps virus |
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DNA viral replication |
Inside the cytoplasm- gets moved to the nucleus |
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DNA viral replication inside the nucleus... |
Gets transcribed into mRNA (just like a host DNA) mRNA gets shipped out with the host mRNA to the ER to be translated by ribosomes Host machinery makes the viral proteins Costs the host lots of energy to do |
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RNA viral replication... |
RNA viruses come in different "flavors" (+) RNA (-) RNA dsRNA Retroviruses |
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Retroviruses viral replication.. |
goes against the grain! Use their sRNA to make sand ---in cytoplasm ---use viral enzyme- reverse transcriptase sand becomes complemented into sDNA --in cytoplasm sDNA then goes to nucleus --follows DNA viral replication process EX: HIV comes in single stranded RNA virus |
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What are Polymerases??? |
enzymes that "polymerize" either DNA or RNA --makes more DNA or RNA --used in REPLICATION and TRANSCRIPTION --needs a template to work off of |
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DNA polymerases |
DNA to DNA aka DNAdependent DNA polymerase Transcriptase (a polymerase): DNA to mRNA tRNAS, rRNA DNA viruses --can use cellular polymerases or can code for their own DNA polymerase and transcriptase. |
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Retroviruses (also RNA viruses) Polymerases... |
Reverse transcriptase.... ...."RNA dependent DNA polymerase" ---uses RNA as a template to go backwards and make DNA ** THESE are unique polymerases and are found only with viruses*** |
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(+) RNA viral replication |
ready to be transcribed genes are in correct direction (5'-3') same polarity as mRNA Ribosomes in the cytoplasm translate the RNA Viral proteins are then able to be packaged |
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(-) RNA viral replication |
not ready to be transcribes genes are going wrong direction ( 3'-5') (-) RNA strand becomes a "template" to make a (+) RNA strand ---reverse and complemented Ready to be translated by ribosmoes |
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Capside Viruses |
mature virions in the nucleus or cytoplasm --many copies ( up to 100,000) So much energy was uses to make these call death usually occurs ( cell lysis) ** Releases mature virions into the environment |
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Enveloped viruses... |
bud out using the host as a new envelope EX: HIV dictate the exit viruses start pushing on cell membrane and "bleb out" |
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Types of ACUTE virus infections: |
influenza, rotavirus, WNV |
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types of PERSISTENT virus infections: |
HIV, Congenital Rubella |
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types of RECURRENT viral infections |
Herpes simplex (cold sores) |
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types of LATENT viral infections |
Varicella Zoster (chicken pox) **insert genetic material into one of your chromosomes--time passes and becomes active as shingles. |
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types of ONCOGENIC viral infections |
Human Papilloma Virus (HPV) |
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Characteristics of Influenza... |
(-) RNA virus contains 11 genes on 8 pieces of RNA roughly 10,000 bases long ---average bacteria about 4.6 million bases --human genome about 3.2 billion bases RNA dependent RNA polymerase makes a mistake once every 10,000 bases mutations occur all the time (poor repair mechanisms) |
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Swine flu |
H1N1 H--- hemagglutinin ------ 16 subtypes N----neuraminidase -----9 subtypes Is the same HN type as the pandemic of 1918 |
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Swine flu pandemic of 1918 |
killed 30-100 million people ---came in two waves infected 500 million most victims were young, otherwise heathy ---influenza typically kills the very young,old or immunocompromised aka "spanish flu" |