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Cameron Lecture study guides > Ch 13 study guide: Viruses, Viroids, and Prions > Flashcards

Ch 13 study guide: Viruses, Viroids, and Prions Flashcards

1
Q

What is the most basic structural definition of a virus?

A

Tiny infectious particle

Obligatory intracellular parasites

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2
Q

Know the 4 general characteristics of viruses

A
  • contain single TYPE of either DNA or RNA
  • contain protein coat
  • multiple only inside living cells
  • contain specialized structures
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3
Q

What is a virion?

A

complete, fully developed viral particle

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4
Q

What does it mean to be in the eclipse phase?

A

complete infective virions are NOT
present

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5
Q

Know the relative size of a virion compared to full cells.

A

Range from 20nm to 1000nm

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6
Q

What is a capsid?

A

-a protein shell or coat
-surrounds the genetic material
-protects the virus
-allows the virus ti infect new cells

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7
Q

What does the Tail Sheath in a virus do?

A

-acts like a needle and forces the genetic material into the host cell

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8
Q

What does the Base Plate in a virus do?

A

helps the virus attach to the host cell

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9
Q

What does the Tail Fiber in a virus do?

A

used to stabilize and attach to the host cell

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10
Q

What is the source of a viral envelope?

A

The viral envelope is derived from host cell membrane.

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11
Q

What is a spike composed of?

A

Carbohydrate-protein complexes that project from the surface of the envelope

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12
Q

What is a role of viral spikes?

A
  • Attach to host cell
  • Means of identification
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13
Q

What types of nucleic acid can be used for the viral genome?

A

DNA or RNA

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14
Q

What is the relative size of the viral genome?

A

Range from 20 nm to 1000 nm in length

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15
Q

What are the two possible viral life cycles?

A

Lytic and Lysogenic cycles

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16
Q

Know the steps of the lytic life cycle.

A
  1. Attachment
  2. Penetration
  3. Biosynthesis
  4. Maturation
  5. Release
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17
Q

What components of the host cell are required (highjacked) by the virus to complete the viral life cycle (think of a few examples)?

A

chromosome

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18
Q

What is a provirus vs a prophage.

A

Provirus infects a eukaryotic organism. Prophage infects bacteria.

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19
Q

What is a prophage?

A

A prophage is the genetic information of the virus after it has been inserted and incorporated into the bacterial DNA which can leave spontaneously

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20
Q

What is a provirus? When is a provirus used?

A

Never comes out of chromosome
Only used in ANIMAL viruses

21
Q

Which can excise from the host’s genome?

A

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

22
Q

Can provirus genes be used by the host cell?

A

Yes

23
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

24
Q

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

A

Lysogenic cells are immune to reinfection by the same phage.

25
Q

How does specialized transduction differ from generalized transduction?

A

Specialized -the bacteriophages pick up only specific portions of the host’s DNA.

Generalized - can pick up any portion of the host’s genome

26
Q

The life cycle of viruses that infect animal cells is very similar to that of phages. What are some of the key differences between the two?

A

Lytic cycle: varion factory and leads to the death of the host

Lysogenic cycle: leads to integration of phage into the host genome. Doesnt kill host

27
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.

28
Q

what can happen to the provirus of an infected cell?

A

replicate while it is still incorporated in the host cell’s genome.

29
Q

What is a prion?

A

Short for Proteinaceous infectious particle

They are misfolded protein

30
Q

What is the mechanism for prion-based diseases?

A

Conversion of normal host glycoprotein PrPC
into PrPsc

31
Q

What are the general characteristics of a prion-caused disease?

A

tremors
uncontrillable laughing

32
Q

What does the abbreviation CJD stand for?

A

Creutzfeldt-Jakob disease

33
Q

What is a viroid composed of?

A

short strand of circular, single-stranded RNA that has no protein coating RNA

34
Q

What do viroid’s infect?

A

Plants

35
Q

Describe why viruses are considered not complete independent cells

A
  • Viruses need a host cell to replicate
  • Cant generate their own food
  • Uses a lot of the host cells compontets to completely replicate
36
Q

What is an advantage of using bacteriophages as a form of therapy?

A

Shown to effectively fight and destroy multi-drug resistant bacteria. Namely, when all antibiotics fail, phages still succeed in killing the bacteria and may save a life from an infection.

37
Q

What is the full name for tRNA and what is its function?

A

Transfer RNA

Bring over amino acids to match up with its corresponding codons to make a protein

38
Q

Retroviruses is an RNA virus that uses and enzyme called

A

Reverse transcriptase to make double stranded DNA
EX: hiv

39
Q

RNA-dependent RNA polymerase is used for

A

making more RNA for their capsids, they then use the rest of the host cells machinery for biosynthesis

40
Q

What is a bacteriophage?

A

viruses that infect bacteria

41
Q

Does a bacteriophage go through the lytic or lysogenic cycle?

A

both

42
Q

What part of the virus contains the viral nucleic acid?

A

Capsid

43
Q

Which bacteriophage life cycle has a prophage?

A

Lysogenic

44
Q

True or False
Antibiotic resistance in a bacterium happens after after an antibiotic has been given

A

False

45
Q

What are some genetic recombination processes that can result in a bacteria having a new trait such as antibiotic resistance or toxic production?

A
  • Conjunction
  • Transduction
  • Transformation
    -Transposons
46
Q

What involves bacteriophages packing up bacterial DNA and transferring it to another bacterial cell?

A

Transduction

47
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

48
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

Cameron Lecture study guides (24 decks)

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