Viruses

Question 1

what is a virus particle called / what does it generally consist of

Answer 1

virion / a viral genome (DNA or RNA) contained within a protein capsid

Question 2

what is a virus

Answer 2

a noncellular particle that infects a host cell and directs it to produce progeny particles (more viruses)

Question 3

which strand is the coding strand / which strand is the template strand

Answer 3

the plus strand / the minus strand - they are reverse compliments of each other

Question 4

what shapes can a virus capsid be

Answer 4

icosahedral, filamentous, and asymmetrical

Question 5

what is an envelope / what are the membrane embedded proteins support and what are they called

Answer 5

a lipid membrane obtained from a host cell / the spike support viral attachment

Question 6

why are enveloped strains typically more sensitive to environmental stress

Answer 6

a naked strain has a hard protein shell that is harder to break down

Question 7

what is a narrow host range / what is a broad host range / what is tropism

Answer 7

when a virus can only infect a single species / when a virus can infect many different species / the number of hosts you can infect

Question 8

what can dictate the tropism of a virus

Answer 8

the presence of a host cell receptor is required to promote genome delivery and can dictate host range

Question 9

what does receptor engagement induce

Answer 9

genome delivery by 1. membrane fusion (of host cell and virus which delivers the genome) 2. viral uptake (uncoating with endosome due to acidification / capsid release and intracellular uncoating due to contact with the nucleus)

Question 10

what can no viruses do, why?

Answer 10

they cannot synthesize their own protein, because they do not encode for ribosomes

Question 11

what is the primary factor that dictates the details of a replication cycles of an animal virus

Answer 11

the form of the animals genome

Question 12

what is the baltimore classification of viruses

Answer 12

1. double stranded DNA 2. Single stranded DNA 3. Double stranded RNA 4. (+)Sense single stranded RNA (read by ribosome) 5. (-)Single stranded RNA (template to make +)

Question 13

what can DNA viruses do

Answer 13

almost entirely use the host cell machinery to replicate

Question 14

what do RNA genome viruses not need

Answer 14

they do not require a DNA intermediate during replication - no RNA polymerase is needed

Question 15

what do RNA viruses use to replicate their RNA genome / what does it do

Answer 15

replicase - a RNA dependent RNA polymerase that is encoed in the viral genome / reads the RNA and converts to dsRNA and converts (-)Single RNA to (+)Sense mRNA using structural proteins

Question 16

which RNA strand can be directly read by the ribosome

Answer 16

(+)Sense RNA can be read directly to create replicase and structural proteins

Question 17

how is a (-)Single RNA replicated

Answer 17

must have replicase encoded into genome in the virion

Question 18

what are RNA tumor viruses / what was identified from these viruses

Answer 18

Murine Leukemia virus and Rous Sarcoma virus that are single stranded RNA viruses that can cause cancer / they have a reverse transcriptase that can convert their RNA into a dsDNA intermediate

Question 19

what are viruses called that use reverse transcriptase to convert RNA to DNA / what doe the DNA intermediate do

Answer 19

retroviruses / integrates into the host cell and can disript certain genes resulting in uncontrolled cellular proliferation

Question 20

what can prevent retrovirus replication

Answer 20

DNA synthesis inhibitors because they stop DNA polymerase which converts the RNA/DNA intermediate into dsDNA

Question 21

what is a pararetrovirus

Answer 21

a dsDNA virus that uses RNA polymerase to convert into dsRNA to then use reverse transcriptase to convert back to dsDNA