lecture 4

Question 1

can viruses diffuse through the membrane

Answer 1

no

Question 2

where does the energy come from that allows a virion into the cell

Answer 2

its built in to the virion

Question 3

what part of the virion attaches to the cell

Answer 3

virion attachement proteins

Question 4

do viruses move on their own

Answer 4

no they gets transmitted through saliva, blood, water, food

Question 5

what is the interaction between the cell and the virion

Answer 5

non specific electrostatic interactions

Question 6

what is often required for virion attachment and entry

Answer 6

virion maturation

Question 7

what needs to happen to viruses after they are released pre maturely

Answer 7

modification called virion maturation or virion activation that is usually protein cleavage

Question 8

3 examples of virion maturation

Answer 8

cleavage of polyproteins
cleavage of virion precursor proteins
processing of envelope

Question 9

4 barriers that viruses have to get past

Answer 9

anatomical barriers
plasma membrane
cytoplasm
nucleus

Question 10

what are the virion attachment proteins for enveloped viruses

Answer 10

membrane glycoproteins

Question 11

what are the virion attachment proteins for naked viruses

Answer 11

spike or surface proteins

Question 12

whats the attachment protein for influenza

Answer 12

hemagglutinin

Question 13

attachement protein for HIV

Answer 13

gp120

Question 14

is receptor binding specific or no

Answer 14

yes

Question 15

what do co receptors do

Answer 15

increase affinity and connection between the virus and the cell after the initial receptor binds

Question 16

avidity

Answer 16

total strength of binding of multiple viral attachment proteins to multiple receptors

Question 17

entry for naked virions

Answer 17

endocytosis and direct entry

Question 18

entry for enveloped viruses

Answer 18

endocytosis and fusion

Question 19

what kind of virus is the only one to fuse

Answer 19

enveloped

Question 20

how do viruses move when attached to the membrane

Answer 20

cellular actin network within the host cell

Question 21

4 ways of entry into cell

Answer 21

uncoating at the plasma membrane
receptor mediated endocytosis
micropinocytosis
caveolin mediated endocytosis

Question 22

is phagocytosis specific

Answer 22

nope

Question 23

3 ways of endocytosis

Answer 23

clathrin dependent endocytosis
macropinocytosis
caveolin dependent

Question 24

during fusion at the plasma membrane, what is the pH

Answer 24

neutral

Question 25

what does macropinocytosis require

Answer 25

signal induction

Question 26

what reached out during macropinocytosis

Answer 26

actin filaments

Question 27

how does a naked virus get into the cytoplasm from an endosome

Answer 27

lysis permeabilization

Question 28

what does caveolin mediated endocytosis need

Answer 28

cholesterol and lipid rafts

Question 29

what is the pH during caveolin mediated endocytosis

Answer 29

neutral

Question 30

where does signalling start when a virus attaches

Answer 30

signalling starts at the plasma membrane by virus receptor binding or through receptor clustering

Question 31

what does virus SV40 attachment do

Answer 31

induces local activation of tyrosine kinases which results in actin filament reorganization

Question 32

what are the 9 steps of virion entry

Answer 32

1. virion diffusion, cell interaction 2. barriers to entry 3. virion attachment proteins 4. receptor binding 5. lateral diffusion 6. vesicular trafficking 7. membrane penetration 8. nuclear import 9. uncoating

Question 33

2 ways of vesicular trafficking

Answer 33

they can enter an endosome and penetrate the cytoplasm when close to their destination they can enter the cytoplasm and use molecular motors (dynein/kinesin)

Question 34

advantages of using endocytic pathway

Answer 34

"free ride" and allows them to hide for a little bit (delays immune recognition)