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Microbiology Exam 3 > Viruses Part 1 > Flashcards

Viruses Part 1 Flashcards

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1
Q

What type of cells can viruses infect? (4)

A

Bacteria, fungi, plants & animals
( any kind of cell really )

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2
Q

What are viruses?

A

Obligate intracellular parasites

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3
Q

Are viruses made of cells? And why?

A

No, they are obligate intracellular parasites

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4
Q

What does it mean that a viruses is obligate intracellular parasites?

A

Viruses can not replicate outside of a host
( they must be inside a host in order to replicate )

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5
Q

Are viruses acellular?why?

A

Yes, because they are not made of cells

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6
Q

Are viruses made of cells ?

A

No

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7
Q

Are viruses living? And why?

A

Yes they are living as long as they are inside a host, however if they are not inside a host they are not, since they don’t replicate outside of one

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8
Q

Are viruses acellular and living? ( when inside a host )

A

Yes

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9
Q

Are viruses small ? ( and what is the size)

A

Yes, 0.3um

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10
Q

Are viruses filterable? Why?

A

Yes because they are very small

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11
Q

How can we filter viruses?

A

Using regular filter paper

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12
Q

Do all viruses contain nucleic acids?

A

Yes

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13
Q

What is the nucleic acid for viruses?

A

Either DNA or RNA
( NEVER BOTH )

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14
Q

Can there be both, dna and rna, nucleic acids for viruses?

A

No

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15
Q

What are nucleic acid surrounded by?

A

Protein coat
( named capsid )^

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16
Q

If viruses have dna nucleic acid, what do we call them?

A

Dna viruses

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17
Q

If viruses have rna nucleic acid, what do we call them?

A

Rna viruses

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18
Q

What is considered to be the first step of classification of viruses ?

A

Whether they are DNA viruses or RNA viruses

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19
Q

What makes DNA and RNA nucleic acids in viruses so speical? (3)

A
  • DNA can be single stranded or double
  • RNA can be double stranded or single
  • viruses only have 1 type, either dna or rna
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20
Q

Nucleic acid are surrounded by a protein called ?

A

Capsid

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21
Q

Since the nucleic acid is surrounded by a protein, what else does it mean? ( proteins are ?)

A

Proteins are made from amino acids

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22
Q

What makes a capsid? ( be more in depth, what covers the entire thing of it? Units ?)

A

Capsomere
are the units to make a capsid^

(So obviously proteins ( amino acids ))

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23
Q

Do all viruses have a capsid?

A

Yes

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24
Q

Why does a viruses need to use a host in order to replicate?

A

Viruses don’t have any ribosomes to make proteins
&
Have very few enzymes for replication so they will need to go into a host to use THEIR enzymes for replication and packaging

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25
Q

Some viruses but not all viruses will have a what to a protein coat? ( capsid)

A

An extra layer surrounding the protein coat

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26
Q

What is this extra layer that surrounds the protein coat ( capsid) called?

A

Envelopes

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27
Q

What are envelopes made of?

A

Phospholipids (lipids)

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28
Q

Capsid are made of ___ & envelopes are made of ___?

A
  1. Proteins
  2. Lipids ( phospholipids)
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29
Q

Where do we usually find phospholipids? ( in bacteria )

A

Cell membranes

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30
Q

Viruses that have an envelope are called?

A

Envelope viruses

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31
Q

Viruses that don’t have an envelope are called?

A

Naked viruses
Or
Non envelope viruses

32
Q

If viruses have an extra layer, the envelope, why are they easier to destroy?

A

Because anything with lipids, it’s much easier to destroy than proteins

33
Q

Lipids envelopes are susceptible to?

A

Disinfectants

34
Q

Why can’t you treat viral infection with antibiotics?

A

Becauses viruses aren’t sensitive to it

( some story behind this )
The reason why we have a trouble with antibiotic resistance is because of this.
We would never, in the past, look if it was a virus or bacteria, so most things just gain resistance since how much we used it on them

35
Q

Are viruses smaller than bacteria? Typically?

A

Yes

36
Q

Why are viruses not considered cells?

A

Because they don’t have ribosomes
&
They can’t keep themselves in a stable state to grow or make own energy

37
Q

What is a complete infectious particle?

A

Virion

38
Q

What is a virion?

A

Complete infectious particle

39
Q

What is a virion made of? (3)

A

Nucleic acid surrounded with capsid and no envelope

Or

Nucleic acid surrounded with capsid with envelope

40
Q

Envelopes virus need their envelopes in order to infect others? Why?

A

Yes, the only reason why envelopes viruses infect is because of that envelope; without it is isn’t comeplete

41
Q

What is the genome for viruses?

A

Contain a single type of nucleic acid
( dna or rna ) NEVER BOTH

42
Q

How many genes in a genome viruses?

A

Varies, though few genes to 250 genes

43
Q

What are the 3 steps to classification of a viruses?

A
  1. Based on nucleic acid content
    (DNA or RNA ) ( single or double )
  2. Capsid ( structure geometric )
  3. Envelope ( have it or not )
44
Q

For nucleic acid, classification section, what can they be?

A

Dna can be single stranded
Rna can be double stranded

Dna or Rna, never both

45
Q

Single stranded RNA viruses, what can we divide them into?

A

Positive sense RNA viruses or Negative sense RNA viruses

46
Q

Is the negative and or positive rna sense viruses only for Single stranded rna ?

A

YES!! ONLY

47
Q

What are single stranded positive sense rna viruses?

A

Can act like a messenger RNA when it infects the cell

48
Q

What are single stranded negative sense rna viruses?

A

When it enters the cell, it just first be copied into a complentary strand, that is the mRNA

Then the translation of proteins can start occurring

49
Q

To summarize, what is the only expection to where we can divide the nucleic acid into 2 groups?

A

Single stranded RNA viruses

50
Q

To summarize, what are the 2 groups the SS rna divide into?

A

Positive sense rna virus
Negative sense rna virus

51
Q

To summarize how do you differentiate between the positive and negative sense viruses for SS rna ?

A

Positive
- can go into the cell and function like an mRNA

negative
- has to first get a complentary strand
( transcribed into a RNA strand )
In order for it to serve as a mRNA

52
Q

Do all viruses have a capsid?

A

Yes

53
Q

What is a capsid?

A

A protein coat surrounding the nucleic acid

54
Q

What does each capsid have that is composed of units?

A

Capsomers

55
Q

Depending on the capsid shape, what do we call it?

A

Symmetry

56
Q

What are the 3 symmetry, capsid shape?

A

Helical, polyhedral, complex

57
Q

What is helical symmetry? (looks like ?) ( 3 )

A

Looks like a rod

Many copies of the same protein wrapped in a helix

Nucleic acid surround by hollow cylindrical capsid

58
Q

What are 2 viruses that fall under helical symmetry?

A

TMV ( tobacco mosaic virus )
Rabies virus

( Ebola too btw !)

59
Q

What is a polyhedral symmetry? ( looks like?) (2)

A

Many sides

Most common shape is
Isosahedral
( 20 sides with 12 corners )

60
Q

What is the most common polyhedral symmetry and what does it have?

A

Icosahedral
( 20 sides with 12 corners )

61
Q

What are the 3 viruses that are icosahedral shapes?

A

Polio virus
Adenovirus
Herpes virus

62
Q

What is complex symmetry?

A

Complicated structure
( variety of shapes )

63
Q

What is the most common complex symmetry?

A

Bacteiophages

64
Q

Bacteriophages shape is complex symmetry but why?

A

Because it has a capsid ( one shape )
A tail ( another shape )
A sheath ( and another shape )

Too many complex structures

65
Q

What is a virus that follows under a complex symmetry?

A

Pox viruses ( small pox )

66
Q

Do all virus have envelopes?

A

Nope

67
Q

What are envelopes made up of?

A

Phospholipids

68
Q

What are the spikes on the envelopes viruses called?

A

Spikes or peplomers

69
Q

What are the spikes ( peplomers ) function for the envelope viruses?

A

Glycoproteins
( receptor of the virus to attach to a cell )

70
Q

Where would the receptors be on a naked virus ?

A

On the capsid

( the reason why is because envelopes have that extra layer, so the spikes are on the envelopes, where as those who are naked don’t, so you’ll find them on the capsid )

71
Q

Are virus specific to a type of cell that they infect ?

A

Yes, very specific
( specific cells )

72
Q

Why are viruses so specific to a certain cell? When it infects the host?

A

Because the glycoproteins, that are found on the surface of the virus, spikes, must find the perfect receptor to attach to the cell

( lock & key moment )

73
Q

How did the lock and key specific receptors come to be for viruses?

A

Evolution

74
Q

If a pathogen can not attach to the surface of the cell, it can not ______

If it can not infect that cell,_____

A
  1. Not infect that cell
  2. It cannot cause disease
75
Q

What is the taxonomy of viruses ?
( how did we use to do it, then better method, to now? ) (3)

A

First
Classified by host
( animal, plant or bacteriophages )

Then
Classified by disease caused
( respiratory dissease or enteric viruses )

TODAY
Classified according to structure
( nucleic acid type, replication strategy, morphology )

Microbiology Exam 3 (12 decks)

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