C-5 Flashcards

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1
Q

capsid

A

protein coat around virus

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2
Q

nucleocapsid

A

capsid and nuclei acid

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3
Q

genome

A

made of RNA and DNA

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4
Q

envelope

A

a phospholipid membrane that surrounds the capsid and acquired from host cell

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5
Q

steps of lytic vs lysogenic bacteriophage replication cycles

A

lytic- fills cells with viruses until it explodes so virus gets out

lysogenic- inserts own DNA into host’s DNA and stays with the cell even as it divides instead of injecting and leaving

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6
Q

what is lysogenic conversion and why is it important in the evolution of human pathogens

A

when the integrated virus gives the host new abilities and characteristics; it stays with the cell as it divides creating these new changes

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7
Q

steps of animal virus replication cycles

A
  1. attach to host cell
  2. enter host cell
  3. replicate genetic material and make protein
  4. assemble new genetic material and proteins together
  5. leave the cell and find a new one
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8
Q

how are viral genomes replicated

A
  1. replicate the genome you came into the cell with
  2. make mRNA that the host cell’s ribosomes can recognize and translate into protein
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9
Q

how are mRNAs produced to make protein capsids from host ribosomes

A

gene expression

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10
Q

how replication occurs for (+)ssRNA

A

reverse transcriptase

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11
Q

how replication occurs for (-) ssRNA

A

RNA-dependent RNA transcriptase

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12
Q

how replication occurs for ssDNA

A

RNA polymerase in nucleus

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13
Q

how replication occurs for dsRNA

A

positive strand of genome acts as mRNA

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14
Q

how replication occurs for dsDNA

A

cellular RNA polymerase in nucleus or viral RNA polymerase in cytoplasm

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15
Q

how replication occurs for retroviruses

A

reverse transcriptase; back in molecular time

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16
Q

What is meant by “positive sense” and “negative sense” single-stranded RNA?

A

negative sense: starts 3’-5’

positive sense: starts 5’-3’

17
Q

how do enveloped viruses enter and exist cells

A

membrane fusion (membrane encloses around virus); endocytosis

budding (steals host cell’s plasma membrane for its own envelope; takes membrane with); lysis

18
Q

how do naked viruses enter and exist cells

A

direct penetration (capsid empties its genome into host cel); endocytosis

exocytosis or lysis

19
Q

how do bacteriophages enter and exit cells

A

inject DNA into cytoplasm of bacterial cell

the mature virions lyse the cell, are released, and go to infect a new cell

20
Q

what enzymes are involved in replicating each type of virus based on its genome

A
21
Q

which enzymes are provided by the host cell and which are produced exclusively by the virus

A

provided: DNA polymerase, RNA polymerase, ribosome

produced: RNA replicase, reverse transcriptase

22
Q

lysogenic viral infections

A

stays with cell as it continues to divide

23
Q

lytic viral infections

A

sometimes the host cell is killed in the process

24
Q

latent viral infections

A

sometimes the host cell survives but the virus remains in the cell

25
Q

what are adhesions? what step of replication are they necessary for?

A

attach step; all viruses to bind to new receptors

26
Q

Describe how we treat and prevent viral infections

A
  • antiviral drugs
  • broad-spectrum strategies
  • vaccines
27
Q

what are nucleoside analogs and reverse
transcriptase inhibitors

A

generic viral enzymes; virus specific enzymes

28
Q

how do antiviral drugs like these (nucleoside analogs and reverse transcriptase inhibitors) work? Why can’t we use antibiotics to treat viral infections?

A

target host cell functions; viruses don’t have cell walls that can be attacked by antibiotics

29
Q

how can viruses cause uncontrolled cell growth and cancer

A
  1. produce a protein that inhibits cell division regulators
  2. integrate into host DNA and into genes that regulate cell division
30
Q

cytopathic effects on viral infection

A

observable morphological changes in host cells that occur because of viral infections

31
Q

plaques

A

produced by lytic HSV from lysed VERO cells in tissue culture

32
Q

syncytia

A

formed by RSV; when the virus fuse host cells together to form one multi-nucleated mega cell

33
Q

inclusion bodies

A

clumps of viral capsid proteins inside the cytoplasm of the host cells

34
Q

Describe the methods used to culture viruses (4)

A

primary; harvested directly from tissue

continuous: derived from cancer cells

embryonated: can grow higher quantities of viruses - used to produce viruses (chicken eggs)

animal models: infect animals with virus

35
Q

viruses

A

nucleic acid and protein

36
Q

viroids

A

pieces of ssRNA that lack capsids and do not code for proteins (only RNA); replicates using host cell RNA polymerase

37
Q

prions

A

only made of protein