L19 Infection and Multiplication

Question 1

steps of a virus life cycle

Answer 1

attachment
entry
synthesis
assembly 
release

Question 2

what happens during attachment

Answer 2

receptor binding proteins on the virion bind to receptors on the surface of the host cell

Question 3

where are the receptor binding proteins present on enveloped cells?

Answer 3

on the envelope

Question 4

where are the receptor binding proteins present on non-enveloped cells?

Answer 4

on the capsid

Question 5

what could a receptor of a virion be

Answer 5

protein molecule

carbohydrate molecule

Question 6

examples of protein molecule recpetors

Answer 6

CD4 (HIV)

ACE2 (SARS-CoV-2)

Question 7

examples of carbohydrate molecule receptors

Answer 7

sialic acid (influenza)

Question 8

what is a co-receptor (example)

Answer 8

CCR5 for HIV

helps with attachment

Question 9

A receptor can be ______ for one virus or ______ viruses can have the same _____

Answer 9

unique
multiple
receptor

Question 10

example of a receptor that is used by Influenza. adenovirus, parainfluenza

Answer 10

sialic acid

Question 11

are receptors present on all host cells and tissues

Answer 11

no

Question 12

three entry methods used by viruses

Answer 12

fusion
endocytosis
direct injection

Question 13

what kinds of virsues tend to use fusion

Answer 13

enveloped

Question 14

examples of bacteria that use fusion

Answer 14

HIV, bacteriophage o6

Question 15

what happens during fusion (HIV example)

Answer 15

the spike proteins bind to the receptors on the host cell (attachment)
the envelope fuses with the plasma membrane releasing the capsid into the cytoplasm

Question 16

endocytosis entry for enveloped viruses

Answer 16

The binding of the spikes to the host cell receptors triggers receptor-mediated endocytosis
-the envelope is degraded by the acidic environment in the endosome and the capsid is released

Question 17

examples of enveloped viruses that enter through endocytosis

Answer 17

Influenza

corona

Question 18

endocytosis entry for non-enveloped viruses

Answer 18

capsid proteins bind to receptors that trigger receptor-mediated endocytosis
-the acidic environment alters the capsid which results in extrusion o the viral genome into the cytoplasm

Question 19

what kind of virus uses direct injection

Answer 19

bacteriophage T4

Question 20

process of direct injection

Answer 20

bacteriophage attaches and a pore forms

-the release of pressure in the capsid results in the genome traveling down the tail and into the cell

Question 21

how do viruses enter plant cells

Answer 21

via open wounds

Question 22

what must a viral genome do once inside the host (synthesis)

Answer 22

replicate
transcribe into mRNA
Translate mRNA into viral proteins

Question 23

what does genome replication depends on

Answer 23

type/configuration (RNA DNA ss ds)

Question 24

where does replication occur

Answer 24

nucleus or cytoplasm of the host

Question 25

what types and configurations of the genome require mRNA to be made

Answer 25

ss/dsDNA and dsRNA

Question 26

what kind of ssRNA does not require mRNA to be made

Answer 26

positive

Question 27

how does the translation of the viral genome occur

Answer 27

hijacks host cell, occurs in the same way as host cell

Question 28

where does translation occur

Answer 28

cytoplasm of host

Question 29

where does assembly occur

Answer 29

cytoplasm, nucleus and/or plasma membrane

Question 30

assembly is ______ and tightly _____

Answer 30

complex | regulated

Question 31

what happens during assembly

Answer 31

viral proteins sequentially react with each other and then with the viral genome to form progeny

Question 32

what happens to the viral protein being synthesised

Answer 32

some are used to make progeny | some are used to evade host defences

Question 33

what is the name of the host proteins used to help in virion assembly

Answer 33

chaperones

Question 34

three mechanisms of release of viruses

Answer 34

lysis budding cell to cell

Question 35

what is required for cell lysis

Answer 35

viral proteins

Question 36

what kind of viruses use lysis for release

Answer 36

bacteriophage

Question 37

examples of viral proteins used in lysis

Answer 37

holin | T4 lysozyme

Question 38

what does holin do

Answer 38

creates holes in bacterial cell plasma membranes

Question 39

what does T4 lysozyme do

Answer 39

dissolves the bacterial cell wall

Question 40

An example of a virus that uses budding as a release mechanism

Answer 40

influenza

Question 41

explain the budding process

Answer 41

- the virus assembles components near or on the plasma membrane and then uses the host cell plasma membrane to form an envelope - enzyme pinches the bud and releases the encapsulated virus

Question 42

two ways cell-cell release can occur

Answer 42

through nerve synapses | plasmodesmata

Question 43

what virus is released via synapses

Answer 43

herpes simplex virus