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BIOL 270 > LEC EXAM #1 CHP. 6 > Flashcards

LEC EXAM #1 CHP. 6 Flashcards

1
Q

Is a virus a living organism?

A

No, viruses are considered acellular and needs a host cell/genome to survive

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2
Q

What is the general structure of a virus?

A
  • Extremely small
  • Bacteriophage structure
  • Capsid protein coat that protects viral genome
  • Has spikes that binds to host cell receptor
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3
Q

Enveloped virus:

A

-Contains genetic material, capsid and lipid bilayer surrounding capsid

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4
Q

Naked/non-enveloped virus:

A
  • No surrounding bilayer

- Contains only genetic material and capsid

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5
Q

Outer shell of a virus is made of?

A

Capsomeres that make up capsid

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6
Q

How are viruses grown in the laboratory?

A

Viruses can be grown in a host (in vivo) or in a petri dish, or flask (in vitro).

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7
Q

How are animal viruses identified in the lab?

A

Virus is grown in vivo (inside the cell) and the cell is observed for cytopathic effects

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8
Q

Mycoplasma vs. viral particles

A

Mycoplasmas have the ability to replicate their own genome

Viral particles have to use host cell to replicate

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9
Q

Mycoplasmas contain:

A

Cholesterol in their cell membrane

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10
Q

Where do mycoplasma cells enter the body first?

A

Mucosal cell in genitals

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11
Q

Mycoplasma characteristics: (6)

A
  • No cell wall
  • Smallest known living organism
  • Pleomorphic
  • Contains cholesterol + other sterols in cell membrane
  • Can survive inside cells
  • Found in soil, plants, and animals
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12
Q

Goal of capsid:

A

To protect genome in cell

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13
Q

Spikes help with:

A

Attachment to the host cell in BOTH enveloped and non-enveloped viruses

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14
Q

What do bacteriophages do?

A

Replicate genetic material and proteins

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15
Q

Spikes are made of:

A

Glycoproteins

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16
Q

Spikes on capsids are:

A

Sheath and tail fibers that attaches and inserts genomes into host cells

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17
Q

Capsid in both enveloped and non-enveloped can cause:

A

Immune response

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18
Q

How do bacteriophages replicate in prokaryotic host?

LYTIC CYCLE

A

Attachment to cell-> infects by penetration of genome-> host DNA destroyed-> new phage particles are made -> lyses and kills cell

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19
Q

Lytic and lysogenic cycle: (temperate phage)

A

Attachment to cell-> phage DNA integrates itself with host DNA-> cell replicates-> under stressful condition phage pops out of genome and produces its parts-> goes through lytic cycle-> lyses and kills cell

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20
Q

Viral infection of eukaryotic host cell: lytic cycle

A
  • Entry is either by endocytosis for non-enveloped or membrane fusion for enveloped
  • Attachment of virus
  • Penetration of virus into membrane
  • Uncoating of viral contents
  • Biosynthesis: RNA enters nucleus and is replicated by RNA polymerase
  • Assembly of new phage particles
  • Release of viral particles into EXF but host cell does NOT die
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21
Q

Family ends in:

A

-virdidae

22
Q

Genes end in:

A

-virus

23
Q

What is the filter porte size for viral isolation from bacterial particles?

A

0.2 microns

24
Q

Viral classification of +ssRNA and -ssRNA:

A

+ssRNA (sense strand)

-ssRNA (anti-sensens strand that is complimentary to sense strand)

25
Q

Goal of temperate phage:

A

To incorporate DNA into host cells DNA

26
Q

In latent infection:

A

Viral loads increased

27
Q

In viral growth:

A

Viral loads deceased

28
Q

HeLa cells by:

A

Henrietta Lax

29
Q

Antibodies are specific for spikes on specific viruses.

T or F

A

True

30
Q

What process happens in HIV?

A

HIV binds GP120 to CD4-> causes it to bind to coreceptor CCR5-> fusion of membranes + viral genetic material inserted into host cell-> dumps reverse transcriptase, integrase, and RNA into host cell-> viral DNA is formed from viral RNA via reverse transcription-> viral DNA combines with integrase to go into nucleus to make viral proteins (capsids and spikes) and viral proteins come out to get used or packaged-> buds off to infect other cells

31
Q

Viruses enter eukaryotic host cell via:

A

Endocytosis for non-enveloped viruses or membrane fusion for enveloped viruses

32
Q

How are viruses treated?

A

With antiviral drugs that interfere with some parts of their “life cycles”

33
Q

What are some cytopathic effects of viruses on human/animal cells? (7)

A
  • Loss of adherence to surface
  • Changes in cell shape from flat to round
  • Shrinkage of nucleus
  • Vacuoles in cytoplasm
  • Formation of cytoplasmic membrane and formation of mutlinucleated syncytial
  • Inclusion bodies in the nucleus or cytoplasm
  • Complete cell lysis
34
Q

What is generalized transduction?

A
  • Transfer and packaging of pure DNA into the virus

- Lytic cycle

35
Q

What is specialized transduction?

A
  • Transfer and packaging of small percentage of bacterial DNA with the viral DNA genome
  • Lysogenic cycle
36
Q

Steps of generalized transduction?

A
  • Phage infects bacterial cell
  • Phage DNA replicates and bacterial DNA is fragmented/hydrolyzed into small pieces
  • During assembly, bacterial DNA fragment accidentally gets packaged into a phage head
  • New phages lyse out and kill cell
  • Phages infect other cells, some of these have bacterial genes that they donate to the new host cell= crossing over of genes
37
Q

Steps of specialized transduction?

A
  • Phage infects bacterial cell
  • Integrates its DNA with bacterial DNA
  • Host cell with phage DNA + bacterial DNA replicates into daughter cells
  • Phage remains dormant until stressful condition arises
  • Goes through lytic cycle*
  • Phage destroys bacterial DNA and replicates its DNA but has some bacterial DNA parts in it
  • Phage DNA is packaged with bacterial DNA
  • Phages lyse out and kill cell
  • Phages infect other cells with mixed DNA-> donates genes to a new host cell= crossing over of genes
38
Q

Difference between packaging processes in generalized and specialized transduction?

A

In generalized transduction, bacterial DNA is packaged separately from phage DNA

In specialized transduction, bacterial DNA is MIXED with phage DNA

39
Q

If you have a -ssRNA virus, what must it do to its genome before it can start making proteins/proteins?

A

Make its +ssRNA compliment

40
Q

Double stranded RNA have:

A

BOTH + and -

41
Q

Single stranded RNA have:

A

+ OR -

42
Q

RdRP:

A

RNA polymerase that does transcription of any - strand and makes it into + strand to make proteins

43
Q

+ssRNA is used:

A

By the host cell’s 80s ribosome to make viral proteins (spikes and capsids)
OR
Make more -ssRNA for new viral particles

44
Q

What is responsible for converting RNA into DNA?

A

Reverse transcriptase

45
Q

In acute infection:

A

Viral load increases immediately

46
Q

In persistant infection:

A

Viral load increases consistently over time

47
Q

Viral growth steps: (4)

A
  1. inoculation: inoculum of virus binds to cell
  2. eclipse: virions penetrate the cell
  3. burst: host cells release many viral particles
  4. burst size: number of visions released per bacterium
48
Q

Antibodies are specific for the spikes on a specific virus:

T or F

A

TRUE

49
Q

Direct assay:

A

Spikes cause hemagglutination of virus and RBC

50
Q

Indirect assay:

A

No hemagglutination because antibodies bind to virus-> virus can’t bind to RBC

BIOL 270 (26 decks)

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