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Microbiology > Ch 13 Viruses Part 2 > Flashcards

Ch 13 Viruses Part 2 Flashcards

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Biology 101 flashcards
1
Q

how do animal phages differ from bacteriophages

A

the mechanisms of entering the host cell are different as well as the synthesis and assembly of new viral components

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2
Q

what are the five stages of multiplication of animal viruses

A

1)attachment 2)entry 3)uncoating 4)biosynthesis 5)maturation/release

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3
Q

describe attachment in animal viruses

A

receptor sites are proteins and glycoproteins
receptor sites are inherited characteristics of the host
varies from person to person (susceptibility)

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4
Q

describe entry in animal viruses

A

receptor mediated endocytosis

fusion

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5
Q

this is how viruses enter eukaryotic cells

molecules bound to proteins on the plasma membrane are take in by infolding of the membrane

A

receptor mediated endocytosis

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6
Q

viral envelope fuses with the plasma membrane and releases the capsid into the cell’s cytoplasm
this is how enveloped viruses enter

A

fusion

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7
Q

describe uncoating in animal viruses

A

separation of the viral nucleic acid from its protein coat once the virion is enclosed within the vesicle
capsid is digested when the cell attempts to digest the vesicle’s contents

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8
Q

describe biosynthesis of DNA viruses

A

DNA containing viruses replicated DNA in nucleus of host by viral enzymes and synthesize capsid into cytoplasm with host enzymes
proteins then join with newly synthesized DNA to form virions (transported to ER)

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9
Q

what are the four steps of biosynthesis of DNA viruses

A

1) transcription then translation
2) synthesis of capsid proteins
3) maturation occurs in nucleus
4) complete virions are released

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10
Q

DNA virus

causes acute respiratory disease (common cold)

A

adenoviridae

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11
Q

DNA virus
skin leisons (pus filled)
small pox/cow pox

A

poxviridae

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12
Q

DNA virus
appearance of cold sores
HHV-1

A

herpeseviridae

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13
Q

DNA virus
warts, tumors, cytoplasmic vacuoles
capable of transforming cells/causing cancer

A

papovaviridae

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14
Q

DNA virus

cause hepatitis

A

hepadinaviridae

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15
Q

describe biosynthesis of RNA viruses

A

several different mechanisms of mRNA formation occur
RNA viruses multiply in the host cell’s cytoplasm
major difference lies in how much mRNA and viral RNA are produced
(once RNA is synthesized maturation is similar)

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16
Q

this is RNA within a virion that can act as mRNA

translated into two proteins which inhibit host synthesis of RNA (catalyze other strands of RNA)

A

sense strand or positive strand

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17
Q

template to produce additional positive strands

A

antisense strand or negative strand

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18
Q

single strand of RNA

contain RNA dependent RNA polymerase that uses negative strand as a template to produce positive strand

A

rhabdoviridae

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19
Q

respiratory and digestive systems of humans

viral mRNA is produced in the cytoplasm

A

reoviridae

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20
Q

enveloped viruses
single positive strand of RNA
two types of mRNA are transcribed from the negative strand

A

togaviridae

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21
Q

carry reverse transcriptase

provirus

A

retroviridae

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22
Q

uses viral RNA as a template to produce complementary double stranded DNA

A

reverse transcriptase

23
Q

never comes out of the chromosome

viral DNA that is integrated into the host cell’s DNA

A

provirus

24
Q

describe maturation and release in animal virus

A

assembly of protein capsid
most capsids of animal proteins are enclosed by envelope
budding

25
Q

what is the envelope protein encoded by

A

viral genes which are incorporated into the plasma membrane of the host

26
Q

process whereby the envelope develops around the capsid

A

budding

27
Q

what are the two methods of release

A

1) assembled capsid pushes through membrane

2) nonenveloped viruses are released through ruptures in host plasma membrane

28
Q

viruses can alter properties via what

A

mutation and genetic reassortment

29
Q

virus may become more viralent

virus may become easily transmitted

A

mutation

30
Q

occurs in segmented viruses
these have genomes divided into different segments (code for different info)
two viruses infecting the same cell
responsible for antigenic shift and antigentic drift

A

genetic reassortment

31
Q

what can plant viruses be recognized by

A

pigment loss, marks on fruit/leaves, tumors, and stunted growth

32
Q

do plants generally recover from viral infections

A

no

33
Q

are all infections bad

A

no

34
Q

what type of viruses are most plant viruses

A

RNA

35
Q

what does plant virus transmission require

A

mechanical damage to plant

  • viruses DO NOT attach to specific cell receptors
  • viruses infect plants through wound in plant cell wall
36
Q

what are virions transferred by

A

wind, animals, seeds, tubers, soil and pollen

37
Q

what are the most important agents of transmission

A

insects that feed on plants (act as vectors)

their feeding by passes cell wall protection and leaves wound that viruses can infect through

38
Q

what are many plant viruses resistant to

A

inactivation

39
Q

what does infection spread from cell to cell through

A

plasmodesmata

40
Q

describe replication in plant viruses

A 
similar to animal viruses
capsid remains outside the cell
filamentous, RNA virus
RNA replication and polymerase
new virions assemble spontaneously
41
Q

group of pathogens much smaller and distinctly different from viruses

A

virions

42
Q

what do viroids consist of

A

small, circular, single stranded RNA molecule

NO protein coat (resistant to proteases)

43
Q

is a single viroid capable of infecting a cell

A

yes

44
Q

what is circular and resistant to nuclease digestion

A

viroid RNA

45
Q

do viroids act as mRNA molecules

A

no

46
Q

how do viroids replicate

A

autonomously in susceptible cells

RNA is replicated by rolling circle method using host RNA polymerase

47
Q

all identified viroids do what

A

infect plants: mechanism unknown, some latent diseases/infections

48
Q

these are proteinaceous infectious agents

A

prions

49
Q

these are linked to a number of fatal human diseases

A

prions

50
Q

what type of disease do prions cause

A

brain degeneration, brain tissue develops sponge-like holes

symptoms may bot appear for years after infection

51
Q

what is currently thought about prion proteins(PrP)

A

they are present in normal form in host animals and exposure to altered PrP causes diseases

52
Q

how did prions arise

A

following mutation to gene encoding normal PrP

53
Q

what did the mutation of PrP cause

A

protein to have different folding properties
the mutated protein is resistant to proteases
resists UV light and nucleases due to lack of nucleic acid

54
Q

what are prions inactivated by

A

chemicals that denature proteins

Microbiology (26 decks)

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