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Introduction to Viruses Flashcards

1
Q

What type of cell can a virus infect?

A

EVERY TYPE OF CELL

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2
Q

How many viruses can seawater contain?

A

100 million viruses/ mililiter

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3
Q

What did Louis Pasteur Postulate? What term did he coin?

A

that a “living thing” smaller than bacteria caused disease. Proposed “virus”, latin for poison

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4
Q

Paleovirology

A

examines genome and how long certain viruses have been in the genome of a specific animal

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5
Q

What are some of the vital roles of viruses in evolution?

A

Infect cells and influence their genetic makeup

Shape the way cells, tissues, bacteria, plants and animals have evolved

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6
Q

What percentage of the human genome consists of sequences that come from viruses? What percentage of bacterial DNA contains viral sequences?

A

10% of human genome

10-20% of bacterial DNA

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7
Q

What does a viruses being Obligate Intracellular Parasites mean?

A

they cannot multiply unless they invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses.

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8
Q

Viruses are the smallest…

A

infectious agents known to man

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9
Q

What are the smallest viruses and their size?

A

parvoviruses, around 20 nm in diameter

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10
Q

What are the largest viruses? the Largest? and their sizes?

What is true about some cylindrical viruses?

A

Mimiviruses; around 450 nm in length
Largest Human Viruses: Poxviruses
Newly Discovered Pandoravirus: nearly 1 um
Cylindrical viruses can be long (800 nm) but narrow in diameter (15nm)

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11
Q

What are viruses not? what do they lack?

A

NOT CELLS

lack any of the protein-synthesizing machinery found in cells

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12
Q

What do viruses contain?

A

only those parts needed to invade and control a host cell
external coating (capsid)
core containing one or more nucleic acid strains of DNA or RNA
sometimes one or two enzymes
sometimes a membrane

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13
Q

What type of DNA can a virus contain?

A

either one or multiple strands of DNA OR one or multiple strands of RNA
One or the other, cannot have both DNA and RNA

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14
Q

What will always be found in a virus, and what will not always be found?

A

Always the protein shell

not always the envelope

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15
Q

What are the two types of coverings in Virus Particles?

A

Capsid

Envelope

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16
Q

What is at the central core of a virus? or can be found there

A 
Nucleic acids (DNA or RNA)
Matrix proteins Enzymes
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17
Q

Capsid

A

Protein shell that surrounds the nucleic acid

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18
Q

Envelope

A

Usually a modified piece of the host’s cell membrane

Determines viral entry strategy; how virus enters the body

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19
Q

Nucleocapsid

A

the capsid together with the nucleic acid

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20
Q

Which viruses only consist of the nucleocapsid?

A

naked viruses, without an envelope

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21
Q

Spikes (peplomers)

A

can be found on naked or enveloped viruses, project from the nucleocapsid or the envelope and allow viruses to attach to host cells

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22
Q

Virion

A

A fully formed virus that is able to establish an infection in a host cell; contain all the structures

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23
Q

Icosahedral

A

spherical, 20 triangles, capsid shape

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24
Q

What is the capsid shape of a Pox Virus

A

Block Shaped

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25
What is the capsid shape of an Ebola Virus
Long Shaped
26
Pleomorphic
envelope has the ability to move around, they can have shapes ranging from filamentous to spherical
27
Where are viral glycoproteins exposed?
on the outside of the envelope
28
Viral Proteins replace
some or all of the regular membrane proteins
29
Helical Capsids
Have rod-shaped capsomers that bond together to form a series of hollow discs resembling a bracelet
30
The nucleocapsids of naked helical viruses are
very rigid and tightly wound into a cylinder shaped package
31
Enveloped helical nucleocapsids
are more flexible than naked viruses' and tend to be arranged as a looser helix within the envelope
32
What remains constant within different helical viruses?
The protein core is the same (helical), though the viruses differ because of the envelope
33
Andovirus
Have DNA in the middle
34
What are some examples of Icosahedral structured viruses?
HIV | West Nile Virus
35
What is the structure of coronaviruses, and a common cold?
Helical Strucuture
36
What family is the ebola virus a part of and what structure is it?
Filovirus family | Has a Shepard's Crook End Structure
37
How many genes are in hepatitis B virus?
4
38
How many genes in some herpesviruses?
Hundreds, they are very complex, meaning they can hide and come back. Very tricky to get rid of
39
DNA viruses can be...
Single Stranded Double Stranded Linear Circular
40
RNA viruses can be ...
``` Double stranded Single Stranded Positive Sense RNA Negative Sense RNA Segmented ```
41
Positive sense RNA
Ready for immediate translation, looks like mRNA ready to go
42
Negative Sense RNA
must be copied before translation can occur
43
Retroviruses
carry their own enzymes to create DNA out of RNA: HIV
44
What are the steps to knowing what the virus is
``` Is it DNA or RNA virus? What type of DNA/RNA is it? Envelope or no Envelope Capsid Structure Types of Spike Protein ```
45
What enzymes can be found in the Virus Particle
Polymerases: synthesize DNA and RNA Replicases that copy RNA Reverse Transcriptase: synthesizes DNA from RNA (HIV)
46
What do retroviruses borrow from the host cells?
tRNA molecules
47
What are the 6 general steps of the animal viral replication cycle
``` Absorption Penetration Uncoating Synthesis Assembly Release ```
48
Absorption Step
Attachment to host cell via spike proteins
49
Penetration Step
Receptor mediated endocytosis, or membrane fushion
50
Uncoating Step
Capsid proteins uncoat releasing nucleic acids DNA viruses travel to nucleus RNA viruses remain in cytoplasm
51
Synthesis Step
Protein Synthesis- manufacturing virus components | and replication of the genome
52
Assembly Step
All components of a viron assemble | Spontaneous for icosahedral viruses
53
Release Step
Budding or cell lysis, cell lysis occurs for non-envelope viruses
54
What is the length for the replication cycle?
8 hours in polioviruses to 36 hours in herpesviruses
55
How do enveloped viruses exit a host cell?
Budding
56
How do non-enveloped viruses exit the host cell?
Lysing the host cell (bursting)
57
Cytopathic Effects (CPEs)
Virus-induced damage to the cell that alters its microscopic appearance
58
What are the types of CPEs
Gross changes in shape and size Development of intracellular changes Inclusion bodies Syncytia
59
Inclusion Bodies
compacted masses of viruses or damaged cell organelles in the nucleus and cytoplasm
60
Syncytia
Fusion of multiple host cells into single large cells containing multiple nuclei
61
Viroids
Composed of Naked Strands of RNA :Lacking a capsid or any coating Significant concert for economically important plants
62
Prions
Composed entirely of Protein Miss-folded proteins cause other normal proteins to miss-fold contain no nucleic acid Cause disease called spongiform encephalopathies
63
Viruses will pull out the host cell proteins and...
Put in their own "spike" proteins, insert them into the membrane
64
Where do the spike proteins bind?
Host cell receptors
65
Tabacco Mosaic Viruses have which type of capsid structure?
Helical
66
What are the two orientations that Viral RNA can have
Positive sense | Negative Sense
67
What does it mean for RNA to be segmented in a virus? Example
meaning you can have multiple pieces of single or double stranded DNA, example is influenza virus

Micobiology (12 decks)

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