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Microbiology > Viruses Acellular Pathogens > Flashcards

Viruses Acellular Pathogens Flashcards

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Biology 101 flashcards
1
Q

Define Virus

A

genetic element that cannot replicate independently of a living ( host) cell

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2
Q

Define virology

A

study of viruses

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3
Q

Define virus particle

A
  • extracellular form of virus

- facilitates transmission from 1 host to another

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4
Q

Define virion

A

infectious virus particles

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5
Q

What are 5 general characteristics of viruses

A
  • Obligatory intracellular parasites ( require living host cells to multiply)
  • contain DNA or RNA
  • contain a protein coat
  • no ribosomes so no protein synthesis
  • no ATP generating mechanism so no metabolism
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6
Q

What 2 factors determine the spectrum of a host xells a virus can infect

A

Determined by specific host attachment sites and cellular factors

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7
Q

Can ppl be immuned to viruses

A

yes, if they don’t have receptors for the virus on therei cells

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8
Q

What are the classifications based on host

A

Bacterial viruses
Animal viruses
Plant viruses

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9
Q

What are 5 viral structures

A

1) nucleic acid
2) capsid
3) nucleocapsid
4) envelope
5) spikes

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10
Q

Describe viral nucleic acid

A

1) DNA OR RNA
2) single stranded or double stranded
3) linear or circular

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11
Q

What is the capsid made of

A

protein coat made of capsomeres ( subunits)

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12
Q

Define nuceocapsid

A

complex of nucleic acid and capsid

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13
Q

What is the envelope made of

A

lipid, protein, and carbohydrates coating on some viruses

classified as enveloped virus or non envelope virus

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14
Q

Define spikes

A

projections from outer surface

has surface proteins

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15
Q

What in the general morphology of viruses based on

A

on the bases of their capsid shapes

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16
Q

What are the 4 types of viruses

A

1) helical virus
2) polyhedral virus
3) enveloped viruses
4) complex viruses

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17
Q

What are helical viruses

A

1) shaped like long rods
2) the capsids are hollow cylinders that has helical structure
3) nucleic acid coiled
ex. rabies and ebola virus

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18
Q

What are polyhedral virus

A

viruses with capsids that are many sided
ex. poliovirus,adenovirus
‘plants,bacteria,anmal viruses has this shape

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19
Q

Define enveloped viruses

A

enveloped and spiked and capsomes
ex. influenza ( helical)
polyhedral ( herpes virus)

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20
Q

Define complex viruses

A

complicated structures
ex. bacteriophage
capsid head, sheath

21
Q

Can we grow viruses in the lab

A

yes
viruses must be grown in living cells
bacteriophages form plaques on a lawn of bacteria
plaque forming unit ( PFU)

22
Q

What are 3 ways of growing animal viruses in the lab

A

1) in living animals
2) in embryonate eggs
3) in cell cultures

23
Q

Describe embryonated egg virus growth

A

virus injected into the egg
viral growth is signaled by changes or death of the embryo
ex. flu virus, vaccines

24
Q

How are animal viruses grown in cell cultures

A

tissues treated with enzyme specific cells
infected cells detected detorioration-(cytopathic effect ( CPE))
continues cell lines are used
transformed cell grow in multiple layers

25
Q

3 techniques for viral identification

A

1) cytopathetic effects
2) seroogical tests ( western blotting)
3) nucleic acids ( RFLPs or PCR)

26
Q

2 requirements for viral multiplication

A

1) it must invade a host cell

2) it must take over the host’s metabolic machinary

27
Q

What are the 3 periods in viral growth

A

Eclipse period
burst
decline

28
Q

What happens in eclipse period

A

when it goes into host cell so unable to detect

29
Q

What happens during burst phase

A

when comes out of host cell

30
Q

What happens during decline in viral growth

A

when there is no more viable host cells will see a decline

31
Q

What are 2 cycles of viral multiplication for bacteriophages

A

1) Lytic cycle

2) Lysogenic cycle

32
Q

Define lytic cycle

A

phage causes lysis and death of the host cell

33
Q

Define lysogenic cycle

A

phage DNA is incorporated in the host DNA

no cell death

34
Q

What are 5 steps of multiplication of T-even bacteriophages (Lytic cycle)

A

1) Attachement: phage attaches to host cell
2) Penetration: phages penetrates host cell and injects its DNA
3) Biosynthesis: phage DNA directs synthesis of viral components by the host cell
4) maturation: viral components reassembled into virions
5) Release: Host cell lyses and new virions are released

35
Q

What are 7 steps of multiplication of animal viruses

A

1) attachment
2) entry and uncoating.virions enter cell and its DNA is uncoated ( fusion or receptor-mediated endocytosis)
3) A portion of viral DNA is transcribed producing mRNA that encodes “early” viral proteins
4) biosynthesis. viral DNA is replicated and some viral proteins are made
5) late translation; capsid proteins are synthesized
6) Maturation virions mature
7) release virions are released via budding

36
Q

What are 2 forms of attachment and penetration

A

1) endocytosis

2) fusion

37
Q

Define endocytosis

A

entry of toga virus by pinocytosis

38
Q

Define fusion

A

entry of herpes virus by fusion

capsid releases its DNA or RNA to work in cell

39
Q

Describe of budding of an enveloped virus

A

host cell plasma membrane create envelope

40
Q

What are 5 possible effects that animal viruses may have on cells

A

1) Transformation into tumor cell ( oncogene activation) TRANSFORMATION
2) Death of cell and release of virus LYSIS
3) Slow release of virus w/o cell death ( Persistent infection)
4) virus present but not replicating ( Latent infection)
5) cell fusion

41
Q

Describe oncogenic DNA virus (2)

A

human papilloma virus ( HPV)- cervical cancer

Hepatitis B virus(HBV)- liver cancer

42
Q

Describe oncogenic rna viruses

A

human t-cell leukemia virus (HTLV-1 and HTLV-2) -LEUKEMIA AND LYMPHOMA

43
Q

Describe viroids

A 
short pieces of naked RNA
small,circular single stranded
plant disease ( potatoe spindle fiber disease)
44
Q

Define prions

A

proteinaceous infectious particles

45
Q

How are prions inherited and transmissible

A

ingestion,transplant, and surgical instruments

46
Q

What are 4 examples of prions

A

1) Mad-cow disease
2) Creutzfeldt-Jakob Disease (CJD)
3) fATAL familial insomia
4) sheep scrapie

47
Q

Define PrPc

A

normal cellular prion protein, on the cell surface

48
Q

Define PrPsc

A

scrapie protein’ accumulates in brain cell, forming plague

49
Q

8 steps how a protein can be infectious

A

1) PrPc produced by cells is secreated to the cell surface
2) PrPsc may be acquired or produced by an altered PrPc gene
3) PrPsc reacts with PrPc on the cell structure
4) Pr Psc converts the PrPc to PrPsc
5) The new PrPsc converts more PrPc
6) the new PrPsc is taken in by endocytosis
7) PrPsc accumulates in endosomes
8) PrPsc cont. to accumulate as the endosome contents are transferred to lysosomes. The result is cell death

Microbiology (16 decks)

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