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MICR > L8 virus and virology > Flashcards

L8 virus and virology Flashcards

1
Q

How many groups in the Baltimore classification system

A

7

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2
Q

List the four traits of viruses

A
  • Virion
  • Capsomere
  • Assembly
  • Capacity to evolve
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3
Q

Decribe the four traits of virsuses

A
  • Virion - extracellular infectious stage
  • Capsomere - all have this cover that protexts nucleic acid in the virion
  • Assembly - infected cells synthesise the virons component parts and then assembly into new virions. (in cytoplasm)
  • Evolve - bc of its min composition of nucleic acids and protein capsomeres, virsus can change through evolution and alter nucleic acid in heritable ways.
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4
Q

What are viruses

A

Obligate intracellular parasites

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5
Q

What requires host cells to multiple with no machinery for protein synthesis and energy production?

A

Viruses

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6
Q

Virus replication simple

A

Assembly of pre-made components

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7
Q

Viruses are infectious particles minimally made up of what two things

A

Nucleic acids and proteins

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8
Q

What is a capsid

A

The protein coat of capsomeres that surrounds the nucleic acids.

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9
Q

What two classes are virions separated on?

A

Enveloped (has proteinaceous lipid bilayer) and naked (doesn not have lipid bilayer)

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10
Q

Name Capsid shapes

A
  • Spherical
  • Helical
  • Icosahedrons
  • bacteriophages
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11
Q

Spherical capsids are actually icosahedrons, which approximate the volume of a sphere yet are constructed from repeated subunits. Spherical capsids are somewhat rigid, whereas helical capsids can be rigid or flexible, depending on the virus.

A
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12
Q

Spherical capsids are somewhat ____, whereas helical capsids can be ____ or ____, depending on the virus.

A

rigid
rigid or flexible

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13
Q

Some bacteriophages combine icosahedral and helical elements, so that their heads that are full of nucleic acids are icosahedral but their tails are what?

A

helical assemblages of specialized tail proteins.

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14
Q

what is a Nucleocapsid

A

In some viruses, the nucleic acid genome and the capsomeres are so intimately associated that their structure is termed a nucleocapsid.

Capsid together with enclosed nucleic acid

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15
Q

Viral Structure

A
  • Complete virus particle
  • Infectious
  • Composed of nucleic acid surrounded by protein coat, for protection
  • Some viruses are enveloped
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16
Q

Viral genomes

A
  • DNA or RNA
  • Sigle or double stranded
  • Linear or circular
  • Several separate segments
  • Few thousand nucleotides to millions (giant viruses)
17
Q

Enveloped viruses may have what shapes of nucleocapsids

A

helical or icosahedral

18
Q

An example of a virus that lacks clearly defined capsids:

A

poxviruses

19
Q

Central dogma of molecular biology:

A

DNA —> RNA —> protein

20
Q

Which scheme is based on the central role of the translational machinery and the importance of viral mRNAs in programming viral protein synthesis?

A

Baltimore classification

mRNA is in the centre, with pathways to mRNA from DNA or RNA genomes.

21
Q

What is a quasispecies

A

Population structure of viruses with a large number of variant genomes (related by mutations).

22
Q

An example of a giant virus

A

mimivirus

23
Q

Cytopathic definition

A

Refers to structural changes in host cells that are caused by viral invasion.

24
Q

Animal cells in culture typically form ____ ____ in which cells introduced into a tissue culture flask attach to and spread out on the specially prepared plastic. As the cells undergo ____, the cell population increases in number until all the cells are touching one another without ________ (A); at this point, contact inhibition (touching other cells on all sides) prevents further population increase

A
  • confluent carpets
  • mitosis
  • overlapping
25
Q

Virus-infected cells may display cytopathic effects that depend on the specific host cell and virus. For example:

A

many viruses cause infected cells to round up and detach from the tissue flask as they die.

26
Q

Virus-induced cytopathic effects (CPE) list

A
  • Synctyia
  • Inclusion bodies
  • Transformed
27
Q

Describe virus-induced cytopathic effects (CPE)

A
  • Synctyia: large multinucleate cells (Herpes)
  • Inclusion bodies: abnormal internal visible structuer and can form in cytoplasm/nucleus (Rabies)
  • Transformed: cancerous cells grow on top of each other instead of responding to contact inhibition as normal cells would.
28
Q

Virus naming schemes

A
  • Disease they cause
  • Human body parts
  • Location found
  • Virion properties
29
Q

Viruses are cultured in animal and human cells in what type of lines

A

Continuous cell lines
* Also cultured in whole animals, primary human cells and diploid cell strains

30
Q

Growth of virus in eggs

A
  • Used to be propagated in chicken eggs
  • Today its used to grow influenza virus for vaccines
  • Egg placed in front of a light source to see and locate non-veined area of allantoic cavity below air sac
  • Virus injected into the cavity where it can replicate
31
Q

Growth of virus in laboratory animals

A
  • Not common now
  • But mainly used as model system to study viral pathogenesis
32
Q

What is a Prion

A

Proteinaceous infectious particle

33
Q

Normal prion

A

Normal prion protein PrP (also known as PrP c ) encoded by PRNP gene is present in neurons as a normal cellular protein in tissue

34
Q

Prion function

A

Unknown but roles include tranport of copper and protection of neurons from injury and formation of neural synapse.

35
Q

Abnormal prions

A
  • More than 30 abnormal forms -> Designated PrP(Sc) -> identified in people with familial disease
  • Cause spongiform encephalopathies: large vacuoles in brain
  • Major features include changes in memory, personality and behaviour; decline in intellectual function (dementia); abnormal movements, particularly difficulty with coordinating movements (ataxia)
36
Q

PrPc mutations that are associated with diseases including what change

A

single amino acid substitutions and truncated protein

37
Q

Formation of anormal PrP(C)

A
  • The abnormal PrPSc can attach to PrPc and promote its transformation into PrPSc
  • Abnormal protein builds up in brain, forming clumps that destroy neurons
  • Loss of these cells creates microscopic sponge-like holes (vacuoles) in the brain, which leads to the signs and symptoms of the disease
38
Q

Prion diseases

A
  • Scrapie (sheep)
  • Cronic wasting disease (deer)
  • Mad cow disease (– bovine spongiform encephalopathy)
  • Fatal familial insomnia (FFI)

MICR (18 decks)

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