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Microbiology > Chapter 13 Viruses > Flashcards

Chapter 13 Viruses Flashcards

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Biology 101 flashcards
1
Q

what are the four general characteristics of viruses?

A
  1. contain single TYPE of either DNA or RNA
  2. contain protein coat
  3. multiply only inside living cells
  4. contain specialized structures that transfer viral nucleic acid to other cells
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2
Q

is the general consensus that viruses are living or non-living? why?

A

non-living
because they can only survive within a host cell

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3
Q

what is the suffix that denotes genus names of viruses?

A

-virus
(ie: Coronavirus)

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4
Q

what is the suffix that denotes family names in viruses?

A

-viridae
(ie: Papilloviridae)

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5
Q

what is the suffix that denotes order names of viruses?

A

-ales

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6
Q

what do we put in front of genus names to classify them?

A

host name
(ie: Human Papillomavirus)

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7
Q

what is the basic structural definition of a virus?

A

obligatory intracellular parasites (tiny infectious particle)

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8
Q

what is the size range of viruses?

A

20 nm to 1000nm in length

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9
Q

are viruses smaller or larger than human RBCs?

A

significantly smaller

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10
Q

what is a virion?

A

complete, fully developed viral particle

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11
Q

describe the appearance of what the nucleic acid of a virion could look like?

A

DNA or RNA
single or double stranded
linear or circular

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12
Q

list the basic components of a virus

A

nucleic acid
capsid
envelopes
spikes

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13
Q

describe the capsid

A

protein coat
contain capsomeres (protein subunits)

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14
Q

describe the envelopes of some viruses?

A

extra protective layer
roughly spherical
forms using host cells membrane
made up of lipids/proteins/carbohydrates

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15
Q

what is a viral spike composed of?

A

carbohydrate-protein projections

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16
Q

what is the role of viral spikes?

A

help attach to host cell
is used as a means of identification

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17
Q

what protects viruses in nonenveloped viruses?

A

just the capsid

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18
Q

what is the source of the viral envelope?

A

host cell’s membrane

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19
Q

what are the two possible viral life cycles

A

lytic cycle
lysogenic cycle

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20
Q

in viral multiplication, what do smallest nonenveloped virions use to replicate their DNA/RNA?

A

everything from the host cell for replication

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21
Q

in viral multiplication, what do larger virions use?

A

few of their own enzymes or mRNA plus the host cells enzymes

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22
Q

what are the 5 basic steps for virus lytic cycle?

A
  1. attachment
  2. entry
  3. replication and gene expression (biosynthesis)
  4. assembly of parts (maturation)
  5. release
23
Q

what does the lytic cycle in simple terms cause to happen to host cell?

A

lysis or cell death of host

24
Q

what does the lysogenic cycle (in simple terms) cause to happen to host cell?

A

host cell to remain active (for period of time)

25
Q

describe the penetration phase of the lytic cycle?

A

bacteriophage release “phage lysozyme” in order to destroy bacterial cell wall for it to inject its DNA into the cell

26
Q

describe the biosynthesis stage of the lytic cycle

A

virus degrade bacteria’s chromosome and break it down in order to rearrange it to make its own DNA with the use of bacteria’s enzymes and ribosomes

27
Q

what is the eclipse period of the lytic cycle?

A

occurs in the biosynthesis stage
is when virions are not yet present within the cell

28
Q

describe the maturation stage of the lytic cycle

A

viral components are assembled into virions

29
Q

describe the release stage of the lytic cycle

A

lysozyme breaks down cell wall
virions are released
plasma membrane lyses

30
Q

what components of the host cell are required by the virus to complete the viral life cycle?

A

nucleotides
enzymes
ribosomes

31
Q

after which step can lysogenic cycle or lytic cycle occur?

A

after injection of viral DNA

32
Q

in lysogenic cycle, what happens after the viral DNA is injected?

A

Phage DNA integrates with bacterial chromosome by recombination to produce a prophage

33
Q

what is the benefit of a bacterial prophage?

A

can give new traits to bacteria

34
Q

what occurs after the prophage is developed within the lysogenic cycle?

A

bacteria reproduce normally and new prophage-containing bacteria form

35
Q

what can occasionally occur during the lysogenic cycle that results in its ensured end?

A

prophage may spontaneously excise (pop out) of bacterial chromosome
this then starts the biosynthesis step of lytic cycle

36
Q

what is a provirus vs a prophage

A

prophage is bacteriophage DNA within bacterial chromosome
provirus is animal virus DNA within animal chromosome

37
Q

which can excise from host’s DNA? provirus or prophage

A

prophage

38
Q

can provirus genes be used by the host cell? can prophage?

A

Either can be used by the cell

39
Q

when does a prophage become active again?

A

Spontaneous event
the action of UV light, or chemicals can lead to excision of phage DNA

40
Q

can a cell infected with a provirus be attacked by virions of the same type?

A

No it cannot

41
Q

What is special about Retroviruses? What is the name of the important enzyme?

A

They use a special enzyme called reverse transcriptase to translate its genetic information into DNA.

42
Q

what can happen to the provirus of an infected cell?

A

it can replicate on its own within the host cell’s genome

43
Q

what is a prion?

A

proteinaceous infectious particles
misfolded proteins

44
Q

what is the mechanism for prion-based diseases?

A
45
Q

what are the general characteristics for prion-based disease?

A

brain damage causing:
tremors
loss of cognitive ability
loss of balance and co-ordination
slurred speech
abnormal jerking movements.

46
Q

what does the abbreviation of CJD stand for?

A

Creutzfeldt-Jakob disease

47
Q

what is a viroid composed of?

A

short pieces of naked RNA
no protein coat

48
Q

what do viroids infect?

A

plants

49
Q

describe why viruses are considered not complete independent cells?

A

viruses need a host cell to replicate
they do not make any/enough of their own enzymes/nucleotides/ribosomes to replicate on their own

50
Q

name two differences between animal viruses and bacteriophages

A

animal viruses infect animal cells while bacteriophages infect bacterial cells

animal viruses (specifically retroviruses) can form a permanent provirus within the animal’s chromosome. while bacteriophages form prophages within bacterial chromosomes that can be excised spontaneously

51
Q

how are the two life cycles of bacteriophages different?

A

lytic cycle: sole purpose is to produce more virions/ immediately kill host

lysogenic cycle: purpose is to integrate its DNA to bacterial chromosome, giving new traits to bacteria/ does not kill host immediately

52
Q

what is an advantage of using bacteriophages as a form of therapy (phage therapy)?

A

bacteriophages only infect specific bacteria, so it won’t harm human cells or own microbiome

53
Q

what is something interesting you learned in class?

A

not to rely to heavily on hand sanitizer because hand sanitizer can cause super bugs and that hand washing is always the best option

Microbiology (23 decks)

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