23: viruses

Question 1

What are some distinctions between viruses and bacteria?

Answer 1

viruses are filterable and cannot replicate in broth

Question 2

What is a virus particle called

Answer 2

virion

Question 3

What are pithovirus?

Answer 3

discovered in ice core, no rRNA, can have virophage

Question 4

What are acute viruses?

Answer 4

rapidly kill their host cells and host, act as predators and parasites to limit host population density, increase host diversity

Question 5

What is a persistent virus?

Answer 5

remain in host where they may evolve traits that confer positive benefits in a virus-host mutualism

Question 6

Why are viruses essential to the biosphere?

Answer 6

help maintain ecological balance, contribute to host diversification, result in nutritional viral shunt

Question 7

What are viruses in our gut called?

Answer 7

caliphates: encode virulence factors that are beneficial for bacteria but toxic to us

Question 8

What are the components of a nonenveloped virus?

Answer 8

genetic material wrapped in a protective capsid, spike proteins attach to host cells and are integrated into the capsid

Question 9

What are the components of an enveloped virus?

Answer 9

have capsids surrounded by an envelope, which are viral proteins embedded In a phospholipid bilayer derived from membrane in host cell. Attached to capsid via matrix protein

Question 10

Why is persistent virus more susceptible to death?

Answer 10

bc it has an envelope and is susceptible to dehydration and loss of structure

Question 11

what is a viroid?

Answer 11

ssRNA virus that infects plants and is transmitted via aphid. Has no capsid, does not encode protein and is replicated by host polymerase, can have catalytic ribozyme that allows for self cleavage and circular genome ligaiton
self complementary
usurp host machine and produce srnas

Question 12

What is a satellite?

Answer 12

sub viral agents that depend on co-infection with a helper virus for replication
- encode structural protein that encloses nucleic acid
-hepatitis delta virus replicated with HBV
-> B provides out capsid, nucleic acids encapsulated by helper virus protein

Question 13

What us a prion?

Answer 13

not a virus derived from protein infection
no nucleic acid components
prp proteins found throughout the body
misfolded, protease resistant PrP cause normal prPs to misfold

Question 14

How many genes are in a giant virus, RNA virus, HPV virus:

Answer 14

e.coli: 5k
giant virus: 300-2500
RNA viruses: 8-12 genes
HPV:
3-5

Question 15

Viral phylogeny

Answer 15

genomic sequencing, based on ortholog comparison, homologies present despite lack of nucleic acid homology

Question 16

What kind of reproduction can viruses do?

Answer 16

Lytic, lysogenic, slow release: virus continually released w/o killing cell

Question 17

What is step one of the virus life cycle?ep

Answer 17

1. attachment

Question 18

What is step two of the virus lifecycle?

Answer 18

eclipse period
2a: disassembly of infectious particle
2b: replication of viral genome

Question 19

Step 3 of virus lifecycle?

Answer 19

latent period
3a: replication of viral structural components
3b: reassembly of replicated pieces into progeny virus particles

Question 20

Step 4 of virus lifecycle?

Answer 20

4a: release of visions from host

Question 21

filamentous phages

Answer 21

capsid has capsomeres, long helical symmetric tubes, surround genome, vary in length and size

Question 22

What are spikes?

Answer 22

viral proteins that attach to host cell and are integrated into capsid