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chapter 6 Flashcards

1
Q

virus

A

obligate intracellular parasite
-can only exist and replicate in a host cell
-specific for host and infect all froms of life
-no animals are immune
-ultramicroscopic
-dont fullfill characteristics of life
-not cellular in nature

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2
Q

characteristics of life

A

-cellular organized
-reproduction
-metabolism
-heredity
-responsiveness
-growth/ develop
-homeostasis
-are they alive? only rlly in presence of host cell

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3
Q

virus genome

A

-dna or rna never both
-single or double stranded
-have been around since life

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4
Q

can viruses synthesize proteins

A

no because they lack ribosomes
-some exceptions

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5
Q

what microscrope can we use for virus

A

electron microscope
-most under .2 microns

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6
Q

virus evoluton

A

virus only carry the genes they need to infect a host cell

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7
Q

virus structure

A

-capsids

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8
Q

capsides

A

-repetitive subunits of proteins/ capsomers
-protein coats that enclose and protect their nucleic acid/ genetic material
-helps deliver genetic material to host cell
-some are surrounding in envelope/ phospholipid bilayer
-helical or iscosahedral

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9
Q

no envelope

A

naked virus

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10
Q

envelope

A

the outside layer that touchs the host cell

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11
Q

helical capsid

A

-capsides in cylinder and the genetic material is wrapped around the cylinder
-naked helical viruses are not human pathogens

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12
Q

icosahedral capsid

A

-20 sides and 12 corners
-1 or multiple proteins to make capsid
-densely packed and can form crystals
-easier to use xray rystallography to get an image of it

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13
Q

viral envelope

A

-mostly viruses that infect animals
-gets envelope when it leaves host cell
-spikes are exposed proteins outside the envelope they help attach to host cell
-

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14
Q

surface proteins of envelope

A

help your immune system recognize the pathogen

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15
Q

nucleases

A

the enzyme that would degrade viruses without the capsid present
-on our hands etc

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16
Q

complex viruses

A

-atypical
-no capside
-ex: poxviruses: covered in dense layer of lipoproteins, have a large genome and structure
-ex: bacteriophage that have a polyhedral nucleocapsid, helical tail and attachment fibers (alien)

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17
Q

viral dna

A

-circular or linear

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18
Q

viral rna

A

-single or double strand
-multiple pieces (pizza that is cut in 8 slices)
-ssRNA (positive sense) or negative sense

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19
Q

positive sense rna

A

rna read by ribosome and translates d into aino acids to make proteins
-rna that foes to ribosome immediatly and the proteins make sense

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20
Q

negative sense

A

-genome if it were to go through ribosome would make a nonsense protein because it is the complimentary strand
-needs to be converted to sense before it is transcribed

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21
Q

in the capsid there are

A

viral proteins that the virus needs to replicate, polymerases, reverse transcriptase (to synth DNA from rna/ aids), RNA dependant rna polymerase (uses RNA to make new RNA) in negative sense, positive doesnt rlly need it

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22
Q

viral classification

A

-family name ends in viridae
-genus: virus
-7 orders, 96 families and 350 genera of viruses
-simple: Herpes simplex 1

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23
Q

absorption

A

virus encountering host cell
-endocytosis or fusion
-endo is used by naked cells
-fusion is for enevelope viruses: phospholipid bilayer or viruse fuses with host cell bilayer bc proteins in virus envelope help mediate this process (fusogenic proteins) draw the membranes together
-

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24
Q

penetration

A

virus taken into vesicle

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25
Q

uncoated

A

-genome leaving capside, vesicle etc

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26
Q

synthesis

A

new genome, proteins, capsides etc

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27
Q

assembly

A

-proteins inserted into cell membrane for the viral envelope

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28
Q

release

A

budding of vesicle
-takes envelop from lipid bilayer
-budding

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29
Q

host range/ tropism

A

-cell or tissue type the organism can infect
-ex: polio infects intestine and motor neurons

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30
Q

why does DNA virus go to nucleus

A

-dna and rna polymerase
-many will use host cells dna and rna polymerase which is in the nucleus
-replicating in cytoplasm it can used enzymes we have
-RNA viruses dont need the polymerase so they will reproduce in cytoplasm

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31
Q

lysis

A

nonenvelpped and complex viruses released when cell dies and ruptures

32
Q

virion

A

-fully formed extracellular cirus particle that is cirulent and able to establish infection in a host cell
-not defective and can infect a host

33
Q

cytopathic effects

A

-virus induced damage on cells
-change in size or shape
-sytoplasmic inclusion bodies (masses of virus particles or damaged cell organelles)
-fusion forms multinucleated cells (syncytia)
-cell lysis
-alter DNA
-transform cells into cancerous cells

34
Q

persistent infections

A

-cell harbors virus and cell is not immediatly lysed/ killed
-length of time varies, weeks or years
-periodic reactivity: chronic latent state (mono/ measles hiding in the brain eventually lethal, chicken pox and shingles)

35
Q

transformation cell

A

-virus turning cell cancerous
-result of altering genetic material bc this alters their normal rules (multiple uncontrolled, cells dont die)
-HPV
-Epstein barr and malaria

36
Q

bacteriophages/ phages

A

-infect viruses
-infect ecoli
-remains out of cell and injects DNA into cell
-lytic cyles

37
Q

lytic cyle

A

-phage recognizes surface features
-bacteria injects genome
-murders host cell
-genome hijacks cell processes and uses it to replicate phages
-protein will weaken cell wall which will burts open destroying host and creating phages

38
Q

temperate phages

A

can do lysogenic cylce

39
Q

prophage

A

genome inserts but the cell is not lysed

40
Q

lysogeny

A

prophage is retianes and copies during normal cell division which transfers the temperate phase genome to all host cell progeny

41
Q

induction

A

activation ogf lysogenic prophage
-host is killing itself to take phage with it so phage kills it first

42
Q

viruses with toxins

A

-get thos etoxins from bacteriophages and those toxins can infect humans
-lysogenic conversions

43
Q

culture a virus

A

-needs to culture host bc they are intracellular parasites
-easiest is a cell culture that support the virus
-bird embryos are eggs that we inject the virus through the shell (flu)
-live animal inoculation only when necessary

44
Q

plaque assay

A

measures ability of virus
-purple cells and observe how the infected cells die, the clearing/ plaque tells us where the virus kills the cells

45
Q

how to detect animal viruses

A

-too small to stain or microscope
-symptoms can help bc many viruses can cause similar symptoms (ex: flu like symptoms)
-pcr (detecting gemone)
-immunoflouresance/ em
-look for part of virus (rapid covid test which binds to the capsid of the covid)
-look for anitbodies in immune system (used post infection)

46
Q

treating viral infection

A

-antiviral drugs have bad side effects (will target host cell too) (ex: AZT for HIV also targets nucleic acid synth: nucleotide analog)
-antibiotics don’t work
-vaccination is best

47
Q

satellite virus

A

dependent on other virus replication
-replicate only in the cells infected with adenovirus
-delta agent (like hepatitis) but it needs hepaatitis to replicate

48
Q

prions

A

-infectious protein that are misfolded and they have no nucleic acids
-one misfolded protein that infects the other
-resistant to sterilization techniques
-cause spongiform encephalopathies / fatal neurodegenerative disease
-common in animals: scapies (sheep), bovine spongiform (mad cow), wasting disease (elk), and creutzfeldt jakob (humans)

49
Q

virus origins

A

many come from humans, some zoonotic

50
Q
A
51
Q

chronic infection

A

-chronically producing new viruses
-slow rate
-symptoms could be absent

52
Q

latent infection

A

-chronic virus that spikes up and becomes acute but then goes dormant
-herpes

53
Q

oncogenic virus

A

causes cancer by bringing an ocogene
-accidently activate oongogene
-uncontollwed growth

54
Q

teratogenic

A

can cross placenta and infect fetus

55
Q

covid

A

-enveloped, nonsegmented positive sense RNA virus (large genome)
-spherical virions
-disease in mammals and birds
-some forms infect people sars 2

56
Q

sars covid 2

A

-entry: envelope fuses to plasma membrane or endocytosis into endosome
-positive sense rna gemone single stranded (nucleic acids that can make genes/ proteins =ORF)
-ORF makes initial proteins that the virus uses to take over cell
-primary translation/ polyprotein procesisng to make first viral protiens
-new rna genome copies
-OFS make compartments in ER (DMV) which protects genome replication from immune bc it needs to make a double strand to duplicate which the cell would attack
-uses compartments to make genome
-DMV parts are packaged and sent to er golgi complex to form where it gets spike proteins
-leaves through exocytosis

57
Q

late stage of virus

A

making structrral proteins/ parts of the virus

58
Q

nsp

A

non structural protein
-covid makes all proteins at once and then protease will cut it at the subunits to make them individual proteins w diff funcitons

59
Q

dmv

A

double membrane vessicle
-covid uses rtc to make genome (RNA)

60
Q

RTC

A

replication transcription complex

61
Q

rna cap

A

lets ribosome bind to it to make proteins
-pink cap on the end of the rtc
-starts translation bc positive sense and cap lets it
-hard to get for viruses so diff method for diff viruses

62
Q

passing stop codon

A

-happens less
-fram shift is a way to control how much protein we are producing that is NSP 12, 13, 14 , 15, 16
-more small nsp bc the knot in the RNA does not cause frame shift and the stop codonis read

63
Q

subgenomic rna

A

all about helping the genes get caps
-genes that make virus structural proteins
-5 prime end cap on RNA that is needed for ribosome translation inititation

64
Q

RBD

A

receptor binding domain

65
Q

three flues

A

A B C
-A is most serious and causes most infections
-based on ribonucleoprotien antigens
-enveloped
-negative sense

66
Q

Flu entering cell

A

three types of proteins inserted into lipid bilayer (hemagglucinin, neuraminidase and M2 ion channel protein

67
Q

flu viral ssRNA is

A

surrounded by nucleoproteins and needs RNA transcriptase
-8 segmentes of ribonucleoprotein
-needs all 8 to infect
-10 genes encoded in the 8

68
Q

flu replication

A

attaches to respiratory cells and segments of RNA enter the nucleus
-virus budds out of cell when done
-positive sense genome makes more negative genome and makes viral proteinsfl

69
Q

flu positive rna

A

intermediary for proteins and rna

70
Q

flu glycoproteins

A

-make the spikes
-hemagglutinin
-nueraminidase

71
Q

hemaglutinning (H)

A

15 subtypes
-most important virulence factor and lets it bind to host cell

72
Q

nueraminidase (N)

A

9 types
-hydroluzes mucus and assists in viral release/ budding

73
Q

antigenic drift

A

constant mutation
-flu makes lots of mistakes which makes mutation
-changes amino acid composition (minor change)

74
Q

antigenic shift

A

-influenza A bc muliple strains infect same cell
-oneof the genes or RNA is substituted with a gene or stranad from another influenza virus from diff host
-huge change
-pizza box: one slice burd flue one slice pig flue etc

75
Q
A

micro (23 decks)

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