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Virology > Week 1 > Flashcards

Week 1 Flashcards

(40 cards)

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1
Q

Define virus:

A
  • small, non-cellular parasite
  • enclosed in a nucleocapsid (protein coat)
  • composed of DNA or RNA
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2
Q

5 ways viruses are useful?

A
  1. Phage-typing
  2. Sources of enzymes
  3. Pesticides
  4. Anti-bacterial
  5. Anti-cancer
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3
Q

What did Chase and Hershey successfully prove?

A

Proved DNA is genetic material through the use of bacteriophages.
- introns were discovered

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4
Q

Virus particles are:
A. virions
B. viroids

A

A. virions
- virus particle that exists outside of the host cell

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5
Q

T/F. Virions do not grow or divide.

A

True

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6
Q

Can viruses synthesize proteins using their own machinery?

A

NO, viruses lack machinery so they hi-jack host DNA

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7
Q

List the 4 types of viral genome.

A

DNA genome
1. Double-stranded DNA
(linear/circular)
2. Single-stranded DNA
(linear/circular)

RNA genome
3. Double-stranded RNA (linear)
4. Single-stranded RNA (linear/circular)

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8
Q

Describe 3 qualities of viral genes.

A
  1. viruses use host cell proteins
  2. viruses code efficiently for protiens
  3. viruses are multifunctional
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9
Q

Are viruses alive? Argue for no.

A
  • viruses do not reproduce by division, they are assembled from preformed components
  • cannot make own energy
  • virions are formed by replication inside the host cell
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10
Q

What do viruses depend on the host for?

A
  • amino acids
  • ribosomes (protein synthesis machinery)
  • energy
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11
Q

List the 4 main types of virion structure.

A
  1. naked
  2. enveloped
  3. icosahedral
  4. helical
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12
Q

What are the components of a virus?

A
  • nucleic acids
  • capsid
  • envelope
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13
Q

What is the function of protein spikes on the virus envelope?

A

Helps virus entry into the host cell

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14
Q

Is a viroid a virus?

A

No

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15
Q

Describe what a viroid is and what it infects.

A
  • self-replicating single-stranded circular RNA
  • no protein coat
  • infects plants
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16
Q

The viral genome is packaged in?
A. envelope
B. capsid
C. nucleocapsid

A

B. capsid

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17
Q

Does the naked or enveloped virus contain the nucleocapsid?

18
Q

The largest of viral genomes is (____) than the smallest genomes of cellular organisms.

19
Q

Do small or large viruses typically infect humans?

Study These Flashcards
A

small viruses
- Hepatitis B

20
Q

What is the region on caspid proteins that allows binding to nucleic acids?

21
Q

Are segmented genomes most common in RNA or DNA viruses?

22
Q

Viruses like (_____) virus package the segments into one virion.

Study These Flashcards
A

Influenza virus

23
Q

Viruses like (_____) virus package the segments into separate virions.

Study These Flashcards
A

brome mosaic virus

24
Q

The brome mosaic virus consists of different RNA segments of different densities. How many separate virions are there?

25
Why is segmentation important?
- potential gene recombination - faster evolution - at least one of each virion must infect the SAME cell
26
The individual protein molecules of capsids are (_____) but are organized into (_____) structures. A. asymmetrical; symmetrical B. symmetrical; asymmetrical
A. asymmetrical; symmetrical
27
The length of the capsid is determined by length of....
the nucleic acid
28
If the capsid has helical symmetry and is in a rod formation describe the bond.
- rigid rod if bonds are strong - flexible rod if bonds are weak
29
Give an example of a capsid with helical symmetry.
Tobacco mosaic virus - single RNA molecule - coat protein subunit (2130)
30
An icosahedron has how many faces and edges?
- 20 faces (equilateral triangle) > three protein molecules per triangular face - 30 edges
31
How many axes of rotational symmetry do icosahedrons have?
- 5 (vertex) - 3 (triangular face) - 2 (edge)
32
Describe the characteristics of a bacteriophage.
1. Icosahedral head 2. tail 3. double-stranded DNA 4. long tail fibers
33
What is the function of short tail fibers?
- recognize binding sites on bacteria (highly specific)
34
Is the lipid membrane located at the virion surface or in the capsid?
Within the capsid
35
Many animal viruses are naked or enveloped?
enveloped
36
Are most virion membranes self made or made from host cell membranes?
made from host cell membranes
37
What are embedded in the virion envelope bilayer that allows for attachment to the host cell?
glycoprotiens
38
Name a way viruses protect themselves whilst outside the host.
occlusion bodies made from protein crystals
39
Occlusion bodies are more common in insect viruses because they are dissolved in what pH level.
alkaline
40
Virus RNA functions as (____) for DNA synthesis and remain attached to the genome in mature virion.
primers

Virology (5 decks)

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