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Micobiology > Introduction to Viruses > Flashcards

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
Q

What is the capsid shape of an Ebola Virus

A

Long Shaped

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26
Q

Pleomorphic

A

envelope has the ability to move around, they can have shapes ranging from filamentous to spherical

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27
Q

Where are viral glycoproteins exposed?

A

on the outside of the envelope

28
Q

Viral Proteins replace

A

some or all of the regular membrane proteins

29
Q

Helical Capsids

A

Have rod-shaped capsomers that bond together to form a series of hollow discs resembling a bracelet

30
Q

The nucleocapsids of naked helical viruses are

A

very rigid and tightly wound into a cylinder shaped package

31
Q

Enveloped helical nucleocapsids

A

are more flexible than naked viruses’ and tend to be arranged as a looser helix within the envelope

32
Q

What remains constant within different helical viruses?

A

The protein core is the same (helical), though the viruses differ because of the envelope

33
Q

Andovirus

A

Have DNA in the middle

34
Q

What are some examples of Icosahedral structured viruses?

A

HIV

West Nile Virus

35
Q

What is the structure of coronaviruses, and a common cold?

A

Helical Strucuture

36
Q

What family is the ebola virus a part of and what structure is it?

A

Filovirus family

Has a Shepard’s Crook End Structure

37
Q

How many genes are in hepatitis B virus?

A

4

38
Q

How many genes in some herpesviruses?

A

Hundreds, they are very complex, meaning they can hide and come back. Very tricky to get rid of

39
Q

DNA viruses can be…

A

Single Stranded
Double Stranded
Linear
Circular

40
Q

RNA viruses can be …

A 
Double stranded 
Single Stranded 
Positive Sense RNA 
Negative Sense RNA
Segmented
41
Q

Positive sense RNA

A

Ready for immediate translation, looks like mRNA ready to go

42
Q

Negative Sense RNA

A

must be copied before translation can occur

43
Q

Retroviruses

A

carry their own enzymes to create DNA out of RNA: HIV

44
Q

What are the steps to knowing what the virus is

A 
Is it DNA or RNA virus?
What type of DNA/RNA is it?
Envelope or no Envelope
Capsid Structure
Types of Spike Protein
45
Q

What enzymes can be found in the Virus Particle

A

Polymerases: synthesize DNA and RNA
Replicases that copy RNA
Reverse Transcriptase: synthesizes DNA from RNA (HIV)

46
Q

What do retroviruses borrow from the host cells?

A

tRNA molecules

47
Q

What are the 6 general steps of the animal viral replication cycle

A 
Absorption
Penetration
Uncoating
Synthesis
Assembly
Release
48
Q

Absorption Step

A

Attachment to host cell via spike proteins

49
Q

Penetration Step

A

Receptor mediated endocytosis, or membrane fushion

50
Q

Uncoating Step

A

Capsid proteins uncoat releasing nucleic acids
DNA viruses travel to nucleus
RNA viruses remain in cytoplasm

51
Q

Synthesis Step

A

Protein Synthesis- manufacturing virus components

and replication of the genome

52
Q

Assembly Step

A

All components of a viron assemble

Spontaneous for icosahedral viruses

53
Q

Release Step

A

Budding or cell lysis, cell lysis occurs for non-envelope viruses

54
Q

What is the length for the replication cycle?

A

8 hours in polioviruses to 36 hours in herpesviruses

55
Q

How do enveloped viruses exit a host cell?

A

Budding

56
Q

How do non-enveloped viruses exit the host cell?

A

Lysing the host cell (bursting)

57
Q

Cytopathic Effects (CPEs)

A

Virus-induced damage to the cell that alters its microscopic appearance

58
Q

What are the types of CPEs

A

Gross changes in shape and size
Development of intracellular changes
Inclusion bodies
Syncytia

59
Q

Inclusion Bodies

A

compacted masses of viruses or damaged cell organelles in the nucleus and cytoplasm

60
Q

Syncytia

A

Fusion of multiple host cells into single large cells containing multiple nuclei

61
Q

Viroids

A

Composed of Naked Strands of RNA :Lacking a capsid or any coating
Significant concert for economically important plants

62
Q

Prions

A

Composed entirely of Protein
Miss-folded proteins cause other normal proteins to miss-fold contain no nucleic acid
Cause disease called spongiform encephalopathies

63
Q

Viruses will pull out the host cell proteins and…

A

Put in their own “spike” proteins, insert them into the membrane

64
Q

Where do the spike proteins bind?

A

Host cell receptors

65
Q

Tabacco Mosaic Viruses have which type of capsid structure?

A

Helical

66
Q

What are the two orientations that Viral RNA can have

A

Positive sense

Negative Sense

67
Q

What does it mean for RNA to be segmented in a virus? Example

A

meaning you can have multiple pieces of single or double stranded DNA, example is influenza virus

Micobiology (12 decks)

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