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Virology > Intro (Lectures 1-3) > Flashcards

Intro (Lectures 1-3) Flashcards

1
Q

Which is true: (a) All viruses make us sick and can be lethal; (b) our immune system can manage most viral infections; (c) humans are usually infected with one virus at any given time; (d) the press is usually correct in their virology reporting; (e) our immune system cannot handle most viral infections?

A

TRUE: our immune system can manage most viral infections

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2
Q

Define “virus”

A

an infectious obligate intracellular parasite comprising of DNA or RNA surrounded by a protein coat and/or envelope

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3
Q

What are the 6 definitive properties of viruses?

A

small particles, infectious obligate intracellular parasites, RNA/DNA genome–> directs synthesis of viral proteins via host processes; virions are formed from pre-formed components; progeny virions are the vehicle for transmission

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4
Q

What type of microscopes can you see viruses with?

A

electron microscope

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5
Q

How many viruses are needed to go into one host cell to cause an infection

A

ONE

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6
Q

What are the 4 characteristics of virus classification?

A

nature of nucleic acid (DNA or RNA), symmetry of capsid (protein shell), presence/absence of lipid envelope, size

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7
Q

What are the 7 classes of viral genomes?

A

ssDNA, dsDNA, (+)ssRNA, (-)ssRNA, dsRNA, dsDNA w/RT, (+)ssRNA w/RT

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8
Q

Which viral genome is essentially mRNA?

A

(+)ssRNA

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9
Q

What is the ONE goal of all viruses?

A

to produce progeny by transcribing mRNA in-order to make their protein to start self-assembly as well as replicate their genome

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10
Q

What provides the answer as to what will be the first biosynthetic event a type of virus needs to accomplish once it gets into the host cell?

A

the Baltimore Classification Scheme

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11
Q

What causes viruses to evolve?

A

environmental pressures

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12
Q

What are the 4 characteristics that identify viruses as “non-living”?

A

cannot make their own building blocks (nucelic acids/amino acids; do not reproduce via cell divison; can’t metabolize or make ATP, relies on host-cell machinery/processes

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13
Q

What are the 2 stages/phases that viruses have?

A

Virion phase and Infected Cell phase

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14
Q

What is the Virion phase of a virus?

A

virus is outside host cell in an inert state just floating; only consists of protein coat/envelope and genome

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15
Q

What is the Infected Cell phase of a virus?

A

when virus is undergoing active production of new progeny by taking over the host cell turning it into a factory

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16
Q

How are viruses simple?

A

all they do is replicate and infect by using host cell processes; they are only active after they replicate in a cell

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17
Q

What are the 3 objectives of virology?

A

how viruses enter cells, how they replicate, how they assemble

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18
Q

What are the 3 states that host cells can be/are regarding viral infection and replication?

A

susceptible, resistant, permissive

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19
Q

What is a susceptible host cell?

A

cell has a functional receptor on its surface that is compatible to a virus that has the matching binding protein

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20
Q

What is a permissive host cell?

A

cell has the capacity to replicate virus

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21
Q

What is a resistant host cell?

A

cell has no receptor or cannot support viral replication

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22
Q

Can a cell be permissible and not susceptible or vice versa?

A

No it needs to be both in order to take up a virus and replicate it

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23
Q

What are 2 things the cell needs to be in order to be infected?

A

susceptible and permissive

24
Q

What type of cells are less permissive to viruses?

A

mature cells

25
Q

What do viruses need to carry out replication? What do they not have that they are going to use from the host cell?

A

ribosomes (protein translation machinery); genetic material replication enzymes (may come with its own); energy (ATP); basic building blocks (ie: nucleic acids and amino acids); and host cell’s transportation system (ie: actin and microtubules)

26
Q

Where do RNA viruses need to replicate?

A

cytoplasm

27
Q

When replicating the RNA, which enzyme do they need to use?

A

RNA-dependent RNA polymerase

28
Q

Where do DNA viruses need to get their genome to?

A

the nucleus

29
Q

When replicating the DNA, which enzyme do DNA viruses need to use?

A

DNA-dependent DNA polymerase

30
Q

What are the cell’s mechanisms that the DNA virus will use in order to transport their genetic material into the nucleus?

A

G-protein and microtubules

31
Q

Where do viral infections typically begin at? Which type of cells are these typically?

A

the surfaces of the body that are exposed to the environment; epithelial and endothelial cells

32
Q

What are the sides of epithelial cells?

A

basolateral surface and apical surface

33
Q

What is the basolateral surface of epithelial cells?

A

faces basement membrane

34
Q

What is the apical surface of epithelial cells?

A

faces lumen or external environment

35
Q

Which side of endothelial/epithelial cells do viruses generally attach to?

A

apical surfaces

36
Q

What is the extracellular matrix?

A

provides mechanical support and holds cells and tissues of the body together

37
Q

What are integrins?

A

proteins that link the basolateral membrane to ECM

38
Q

What are cadherins?

A

proteins that hold together cells such as epithelial cells via tight junctions

39
Q

What type of cells are normally detached?

A

cancerous cells

40
Q

Why do cells generally need to be attached? What happens to them when they become detached?

A

Cells need to be attached so they can communicate signals to each other and maintain survival; if they detach, they will undergo apoptosis

41
Q

What are some of the proteins that make up the ECM?

A

collagen and fibronectin

42
Q

In which way do phospholipids move?

A

laterally

43
Q

What is a distinct characteristic about phospholipids?

A

amphiphatic molecules that have a non-polar and a polar side

44
Q

What are 2 types of membrane proteins?

A

integral membrane proteins and indirectly anchored proteins

45
Q

What are integral membrane proteins?

A

can cross part of or the entire span of the lipid membrane

46
Q

What are indirectly anchored proteins?

A

can be anchored onto the lipid membrane by a lipid molecule

47
Q

What are the 7 steps in the Infectious Cycle?

A

Attachment | Penetration/Entry | Uncoating | Genome Expression/Replication | Assembly | Maturation | Egress/Exit

48
Q

What is the “Attachment” step?

A

virus binds to cell surface receptor

49
Q

What is the “Penetration/Entry” step?

A

virus breaks into cell by crossing plasma membrane (actin remodeling) and then needs to break out of endosome to get into cytoplasm

50
Q

What is the “Uncoating” step?

A

virus gets rid of capsid and localizes its genome

51
Q

What is the “Viral Gene Expression/Replication” step?

A

genome needs to be transcribed and translated to make viral proteins and then it needs to be replicated

52
Q

What is the “Assembly” step?

A

newly synthesized viral proteins and replicated genome will then be assembled de novo

53
Q

What does “de novo” mean in regards to viral assembly?

A

no proteins assisting the virus to get assembled (mostly occurs via signaling sequences)

54
Q

What is the “Maturation” step?

A

proteins within newly assembled virus will undergo proteolytic cleavage to increase its stability

55
Q

What are 2 ways viruses leave mammalian cells?

A

lysis or budding off/secretion

56
Q

What are the 3 conclusions of the Burst concept?

A

one cell makes hundreds of progeny and each cell makes around the same number of viruses; the cell has a finite number of progeny produced per cell

57
Q

What does “Burst” mean?

A

the progeny yield from one cell = one viral generation

Virology (23 decks)

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