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Micro-101 Exam 3 > Chap 14 - Viruses > Flashcards

Chap 14 - Viruses Flashcards

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1
Q

Name three virologists who contributed to the early understanding of viruses. Hint: they studied the Tobacco Mosaic Virus.

A

IBM: D. Ivonwsky, and B. Beijerinck, A. Mayer

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2
Q

What was on of the first viruses studied?

A

Tobacco Mosaic virus.

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3
Q

Viruses are considered nonliving and are composed of nucleic acid and ___.

A

Protein (protein coat aka capsid)

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4
Q

Walter Reed studied this disease which goes to the liver, causing jaundice. Hint:mosquito is vector.

A

Yellow Fever

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5
Q

Twort and d’Herelle studied viruses that infected bacteria. What are those viruses called?

A

bacteriophages

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6
Q

The Viral genome contains either ___ or ___, but not both.

A

DNA or RNA

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7
Q

Name for the protein coat made up of capsomeres?

A

Capsid

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8
Q

T or F - Viruses lack the machinery for generating energy and large molecules

A

True

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9
Q

Receptor binding proteins that help the virus attach to the host cell as well as facilitate entry (can also help with release of virus)

A

Spikes

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10
Q

_____ + ____ = virus

A

capsid + genome

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11
Q

The first human virus discovered was? HInt: mosquito vector

A

Yellow fever

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12
Q

The first plant virus was?

A

Tobacco mosaic virus

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13
Q

Bacteriophages are what?

A

A bacteriophage is a virus that infects and replicates within a bacterium

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14
Q

What are the three shapes of viruses

A

Helical. Icosahedral, and Complex

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15
Q

This shape is a 20 sided polygon

A

Icosahedral

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16
Q

This shape has both helical and icosahedral

A

Complex

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17
Q

Do viruses have tissue specificity?

A

Yes- Tissue Tropism

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18
Q

The host range refers to what; and is based on what?

A

Organisms that the virus can infect. Capsid, envelope or spike structure.

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19
Q

T or F - Viruses do not need a specific receptor in order to invade the host cell.

A

False - they do need specific receptors.

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20
Q

Name the committee who is developing a classification system for viruses

A

International Committee on Taxonomy of Viruses (ICTV)

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21
Q

How are viruses currently classified?

A

By their genomes (DNA vs RNA)

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22
Q

T or F - RNA Viruses can be either single or double stranded RNA genomes

A

True.

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23
Q

Where is virus RNA replicated?

A

At the host cell ribosomes (in cytoplasm)

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24
Q

Where is virus DNA replicated?

A

In the Host cell DNA (nucleus if euk)

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25
Q

What is a retrovirus and which is the most famous retrovirus?

A

HIV

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26
Q

Retroviruses are replicated indirectly through DNA intermediate using an use this enzyme called?

A

Reverse transcriptase enzyme. RTE

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27
Q

Viral Replication follows these steps:

A

Attachment - Penetration - Biosynthesis - Assembly (maturation) - Release (APBAR)

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28
Q

If the virus does not go to directly to the biosynthesis phase, what is this called?

A

Latency

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29
Q

This stage of replication “makes the parts” of the virus

A

biosynthesis

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30
Q

Replication of bacteriophages follows what two cycles?

A

Lytic (virulent) and Lysogenic (lazy)

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31
Q

Herpes is an example of the “lazy” phase of bacteriophage replication. What is the name for this phase?

A

lysogenic

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32
Q

Steps in Animal virus replication involve:

A

Attachment by receptors - Penetration (capsid and genome get in together!!!) - UNCOATING (Capsid off -releases genome) - Biosynthesis - Assembly - Release by budding

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33
Q

In Animal virus replication, where does the RNA replicate?

A

In the cytoplasm

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34
Q

Why are latent proviruses immune to the host body’s defenses?

A

because they are a part of the DNA. THe immune system looks for foreign protein, caps or spikes.

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35
Q

Antibodies are what?

A

Proteins made by immune system, they can clump up virus for removal.

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36
Q

When attempting to detect a viral infection, a light microscopes can be used to look for what?

A

CPE - cytopathic effects (damaged host cells)

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37
Q

In a primary cell culture, cells form a ______ in a culture dish?

A

Monolayer

38
Q

In viewing a plate containing a monolayer of animal cells, what do you look for formation of in terms of virus detection?

A

formation of plaques (clear zones where the virus has killed the host cell)

39
Q

The only vaccine that exists to combat cancer is for what virus?

A

HPV (Human Papilloma Virus)

40
Q

(SKIPPED SLIDE) Protooncogenes can be transformed to oncogenes by:

A

Radiation - chemical carcinogens - DNA damage - viruses

41
Q

The construction of the capsid’s amino acids protect viruses from _____, ______, and _______.

A

Temperature, pH, and other environmental fluctuations

42
Q

The completely assembled and infectious virus outside its host cell is known as a:

A

A Virion

43
Q

Archaeal viruses are morphologically unique because why?

A

They often have spindle shapes

44
Q

Even within its host range (rang of organisms it can infect) there are limitations as to which TISSUE it can infect. This limitation is called?

A

tissue tropism

45
Q

Can a negative RNA genome virus be directly transcribed into protein?

A

No. Only a positive single strand can be read by ribosome and converted immediately in to protein.

46
Q

Negative Strands of RNA viruses must go through a step to be converted into proteins. What is the step?

A

First converted to (+), then can be made into protein (spikes, capsids, etc.)

47
Q

What is the name for an RNA virus that can convert back into DNA?

A

Retroviruses (retro = go backward)

48
Q

The viral DNA of a bacterial virus that is inserted into the bacterial DNA and is passed on from one generation to the next during binary fission.

A

Prophage

49
Q

This is a malignant tumor that begins growing in connective tissue such as muscle bone, fat, or cartilage.

A

Sarcoma

50
Q

These are tiny fragments of infectious RNA, that lack capsid and spikes, and cause diseases in crop plants.

A

Viroids (infectious RNA that lacks capsid and spikes)

51
Q

One hypothesis about viroids suggests that they originated as what?

A

Introns

52
Q

Infectious proteins (lack DNA and RNA)

A

Prions

53
Q

Early virologist who coined the term virus

A

Beijernick

54
Q

What are signs of Tobacco Mosaic Disease

A

Tobacco leaves shrivel and assume mosaic appearance

55
Q

Which is smaller, bacteria or virus?

A

VIrus

56
Q

How are viruses cultured?

A

Egg method developed by woodruff and goodpasture

57
Q

Who developed a method to mass produce vaccine?

A

Salk

58
Q

True or False: Viruses replicate by taking over the host cell

A

True

59
Q

Does Nucleic Acid occur in single or double strand? Linear or circular?

A

Both. Both.

60
Q

A virus without an envelope is referred to as a ___________ virus.

A

Naked

61
Q

Flu Viruses are made of _NA. Herpes is made of _NA.

A

Flu = RNA/ Herpes = DNA

62
Q

Where does the virus obtain materials such as lipids and proteins?

A

From host cell

63
Q

Does shape determine where the virus will attach?

A

Yes

64
Q

How does viral structure determine host range and tissue tropism?

A

HR: is based on virus’ capsid or envelope.
TT: Specific receptors are required. WIthout receptor and complementary protein, virus cannot infect.

65
Q

How do antivirals work?

A

remove the receptor, virus cannot bind

66
Q

In Viral replication, what takes place during biosynthesis ?

A

Nucleic acid is replicated. Viral proteins, including capsid and tail fiber/spike proteins are made.

67
Q

What takes place during assembly?

A

Capsid proteins and nucleic acid are assembled into nucleocapsids.

68
Q

What may happen as the virus is released during replication?

A

Possibly kill host as rips through membrane.
Damage the host
VIRUS MAY STEAL NUCLEOTIDES, ATP and ENZYMES!

69
Q

What is the name for a virus that has been emptied of it’s DNA and is now worthless?

A

Ghostphage

70
Q

How does a virus benefit from the lysogenic cycle (lazy cheetos)?

A

Once the prophage (dna->bacterial chromosome) is inserted, it is copied during fission. Also, immune system cannot detect.

71
Q

Herpes is an example of a virus that leaves the ______ cycle for the _______ cycle.

A

Lysogenic; lytic

72
Q

The lytic cycle includes the steps from penetration, through release (the active assembly and maturation of viruses) in an an animal cell? Many virions are produced.
This infection is considered?

A

productive

Produces virus, they are productive at maturing…

73
Q

In animal cells, at the attachment site, the virus enter the cell through endocytosis or though fusion with membrane. What is the next step that happens in animal cells but not bacterial cells?

A

uncoating! Once inside the cell, the capsid disassembles from the genome, genome then heads for replication or transcription.

74
Q

Where in an animal cell are “parts” made for the virus?

A

Cytoplasm. Parts are protein which is made by ribosomes in the cytoplasm.

75
Q

Do proviruses hang out and wait or are they active?

A

Hang out and wait.

76
Q

What is it called when a virus fuses with the plasma membrane and then releases the virion outside of the host cell?

A

budding

77
Q

What is the difference between a retrovirus and a provirus?

A

A retrovirus is an infectious unit that exists outside of a cell and has a protein coat and a lipid membrane

A provirus is a integrated retrovirus in the host DNA.

78
Q

Which virus encodes a repressor protein that prevents activation (hint: prevent activation = not active)?

A

provirus

79
Q

What are two possible types of infections one may experience?

A

Productive or Latent

80
Q

If a cell is not destroyed after the virus exits, will it be attacked again?

A

“Why the F not?” - Dr. Pepper

Yes!

81
Q

How are most viral diseases diagnosed?

A

Symptoms (measles rash - herpes blister - etc)

Light microscopes (view syncytia)

electron microscopes (view cells)

Serology (looks for large amount of antibodies in the blood. If present (+) for virus)

82
Q

How do antibodies, which are made by the immune system, remove virus?

A

Clumps to virus, macrophage destroys

83
Q

A clone of abnormal cells…

A

tumor

84
Q

Uncontrolled growth and spread of cells…

A

cancer

85
Q

Difference between benign and malignant

A

Benign - non cancerous

Malignant - metastasizes

86
Q

Name for viruses that cause cancer…

A

Oncogenic virus

87
Q

How do viruses cause cancer?

A

Interrupt meitosis (causing uncontrolled cell division)

Activate oncogenes

88
Q

What is it called when 2 or more viruses exchange info?

A

genetic recombination

89
Q

Can genetic recombination expand the host range of a virus? New viruses?

A

Yes. Yes.

90
Q

TSE: Transmissible (from one organism to another) spongeform (turns brain to a sponge) encephalopathies (inflammation of brain) is related to what infection?

A

Infection caused by prion

91
Q

Stanley Prusiner discovered the proteinaceous infectious particle known as?

A

Prion (Prusiner…prius…prions)

92
Q

How do prions damage brain cells?

A

abnormal prions change the shape of normal protein in the brain (normal prions).

Micro-101 Exam 3 (6 decks)

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