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Micro Test 3 > Introduction, Classification, and Structure > Flashcards

Introduction, Classification, and Structure Flashcards

1
Q

Give a simplified description of a virus.

A

Nucleic acid surrounded by a capsid (protein).

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2
Q

A virus may or may not be surrounded by an __________.

A

Envelope

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3
Q

Viruses are ____________ intracellular parasites. What does this mean?

A

Obligate - This means that it uses the host cell as an energy source and uses the cell to facilitate replication.

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4
Q

T/F Viruses are both eukaryotes and prokaryotes.

A

False - They are neither. They are just particles, not cells.

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5
Q

What is the smallest virus and how big is it?

A

Poliovirus is 30 nm in size (100 times smaller than E. coli).

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6
Q

What is the largest virus and how big is it?

A

Vacciniavirus is 300 nm in size.

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7
Q

Why do viruses need a host cell?

A

They lack metabolic systems and most enzymes for protein synthesis. They use the hosts energy source (ATP).

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8
Q

What all is needed from the host cell by the viruses? (Hint: 3 groups of things)

A
  1. Building blocks (amino acids, nucleosides)
  2. Protein Synthesis Machinery (Ribosomes)
  3. Energy (ATP)
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9
Q

T/F - Viruses reproduce sexually, asexually, or by binary fission.

A

False - They don’t replicate they only ASSEMBLE.

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10
Q

T/F - Viruses have limited tropism.

A

True - Most viruses can infect only a limited number of cell types (Unlike many bacteria that can infect different parts of the body.)

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11
Q

How does the location of viral assembly/reproduction protect the virus?

A

It is intracellular so the virus is protected from some of the aspects of the immune response.

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12
Q

What type of genetic material will a virus contain?

A

Either RNA or DNA but rarely find both (CMV has a DNA genome and RNA transcripts). The four categories of viral genomes is dsDNA, ssDNA, dsRNA, and ssRNA.

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13
Q

What of the four genomes found in viruses are unique to viruses?

A

ssDNA, dsRNA, and ssRNA

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14
Q

What are the 3 major categories of proteins encoded in viral genomes?

A
  1. Enzymes required for copying nucleic acids (Replication of the genome and the production of mRNA)
  2. Proteins used in the assembly of progeny virus
  3. Some large viruses encode proteins that interfere with the host defenses
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15
Q

T/F - All viruses, with one exception are diploid.

A

False - All are haploid (contain one copy of the genome) with one exception.

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16
Q

What is the exception of viruses that is diploid (contains 2 identical copies of the genome)?

A

Retroviruses (HIV)

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17
Q

What does BBV stand for?

A

Blood-bourne viruses

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18
Q

What is the greatest threat of infection for a dentist and poses a potentially serious health hazard?

A

BBVs

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19
Q

The risk of transmission of a BBV is greatest from the __________ to the __________. Not the other way around.

A

From the patient to the doctor.

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20
Q

Transmission often follows an _______________ injury.

A

Inoculation

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21
Q

What is an inoculation injury?

A

Any instance where an object or substance contaminated by blood or other body fluids either breaks the integrity of the skin or mucosa OR comes into contact with the eyes.

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22
Q

Give some examples of contaminated objects.

A

Needles, teeth, bones, instruments, etc.

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23
Q

What are the 3 major BBVs that pose a health hazard for dentists following an inoculation injury?

A
  1. HBV
  2. HCV
  3. HIV
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24
Q

What are the chances of contracting the 3 major BBVs?

A
  1. HBV - 1/3 chance if patient is e antigen+
  2. HCBV - 1/30 chance
  3. HIV - 1/300 chance (1/2000 for mucocutaneous exposure without inoculation.)
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25
Q

What should you do to reduce the risk of becoming infected after an inoculation injury?

A

Wash are with soap and water (don’t scrub), don’t suck on the wound, irrigate eyes after removing contacts, seek medical advice for possible prophylactic therapy

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26
Q

What are the families of the most common cause of primary viral infections of the oral cavity?

A

HHV and HPV.

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27
Q

What is the biological classification system order?

A

Order, Families, Subfamilies, Genera, and Species

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28
Q

What are the suffixes for each of the parts of the classification system?

A
  1. Order: -virales
  2. Families: -viridae
  3. Subfamilies: -virinae
  4. Genera: -virus
  5. Species: Name of the virus, followed by the word virus
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29
Q

What is Adenoviridae?

A

Mastadenovirus - family of animal DNA viruses

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30
Q

What is Hepadnaviridae?

A

Hepatitis B virus - family of animal DNA viruses

31
Q

What is Herpesviridae?

A

Herpes simplex virus (HSV) and Epstein-Barr virus (EBV) - family of animal DNA viruses

32
Q

What is Papovaviridae?

A

Human Papilloma Virus (HPV) - family of animal DNA virus

33
Q

What is Flaviviridae?

A

Hepatitis C virus, Yellow fever virus, and West Nile virus - family of animal RNA viruses

34
Q

What is Orthomyxoviridae?

A

Influenza virus - family of RNA virus

35
Q

What is Paramyxoviridae?

A

Mumps, measles, and respiratory syncytial virus (RSV) - family of RNA virus

36
Q

What is Picornaviridae?

A

Hepatitis A virus, poliovirus, rhinovirus, coxsackie, and enterovirus - family of RNA virus

37
Q

What is Reoviridae?

A

Rotavirus - family of RNA virus

38
Q

What is Retroviridae?

A

HIV, human T cell lymphotropic virus (HTLV) - family of RNA viruses

39
Q

What is Togaviridae?

A

Rubella and hepatitis F virus - family of RNA viruses

40
Q

What is a capsid?

A

Protein coat that confines the nucleic acid and serves to protect the viral genome.

41
Q

T/F - The protective capsid of a virus may be involved in host cell recognition.

42
Q

What different forms can the capsid take?

A

The capsid may be a nucleocapsid, where proteins interact with the nucleic acid in a helical formation or the capsid structure may be a protective shell.

43
Q

What are the two most common types of symmetrical arrangements of capsomeres?

A

Helical or icosahedral.

44
Q

Individual subunits assemble to make the _____________, which comes together to make the capsomeres.

A

Protomer (So, the way it works is Subunits -> Protomer -> Capsomeres -> Capsid)

45
Q

T/F - The virus produces large quantities of smaller subunits that thermodynamically assemble into a favorable energy state producing the essential protein capsid.

46
Q

Is there a correlation between thermodynamics and viral architecture?

47
Q

T/F - Viruses are known to infect every type of cell?

48
Q

Do eukaryotic cells have RNA-copying enzymes? Why would this matter?

A

No, eukaryotic cells don’t have RNA-copying enzymes. Some virus genomes are made of RNA, so this type of virus needs to provide the enzymes for copying it into mRNA and then copy it to make more RNA genomes.

49
Q

What 3 things are viruses categorized by and which one is used for viruses only?

A
  1. Genetic similarities
  2. Structural morphology
  3. Host range (viruses only)
50
Q

What are the functions of the capsid?

A

To protect the genome and to aid its entry into a host cell where it can replicate and make new virons.

51
Q

T/F - Only RNA viruses have helical symmetry.

52
Q

If its human and helical, its ___ and ________.

A

RNA and Enveloped

53
Q

Do all human viruses with a helical capsid have an envelope?

54
Q

Some viruses are neither helical or polyhedral and are considered ___________.

55
Q

The capsid protein coat may be surrounded by an envelope of _____ __________ and __________.

A

Lipid membrane and protein

56
Q

What type of viruses are more common to have envelopes?

A

Animal viruses

57
Q

Wheat is an envelope composed of?

A

Host cell membrane and viral proteins

58
Q

Viruses without an envelope are referred to as _____ viruses.

59
Q

Does the capsid assemble spontaneously or does it need enzymes and energy?

A

Spontaneously/automatically without the use of energy or an enzyme.

60
Q

Does capsid assembly occur before or after a virion acquires an envelope?

A

It occurs before

61
Q

What type of proteins make up the majority of the envelope?

A

Glycoproteins

62
Q

Glycoproteins that make up an envelope will be of what origin?

A

Viral and Host

63
Q

T/F - Envelope proteins play a role in host cell recognition and usually binding to host cells upon infection.

64
Q

Can viral DNA be continuous or segmented?

65
Q

What are some examples of viruses with helical symmetry?

A

Rabies, SARS, measles, mumps, influenza, and Ebola.

66
Q

The icosahedral geometry can be represented as __ ___________ _______ placed around the surface of a sphere.

A

20 equilateral triangles

67
Q

T/F - Capsid surfaces are always smooth.

A

False - They are not always smooth and they sometimes vary in their topography. There may be canyons, hollows, ridges, and/or spikes present

68
Q

What are the possible sources for the envelope of a virus?

A

Nuclear membrane, outer membrane, golgi membrane, or vesicle membrane - depends on the virus

69
Q

Glycoproteins carry _________ ________ allowing the virus to attach to susceptible cells and some possess fusion activity that allows the membrane of the virus to fuse with the cell membrane to facilitate entry and infection.

A

attachment domains

70
Q

What type of protein is on the surface of a virus and is a primary target for the immune system?

A

Glycoproteins

71
Q

Where do proteins become glycosylated?

A

As they pass through the endoplasmic reticulum and the golgi apparatus.

72
Q

What type of conformation is DNA in viruses (multiple answers)?

A
  1. ssDNA Linear (+ or - sense)
  2. ds Linear
  3. ds Circular
73
Q

What type of conformation is RNA in viruses (multiple answers)?

A
  1. ssRNA Linear (+ or - sense)

2.

Micro Test 3 (4 decks)

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