fundamental virology - L6A

Question 1

what is a virus?

Answer 1

a protein shell with genetic material

intracellular parasite

Question 2

what is a virion?

Answer 2

extracellular form of a virus

Question 3

what is a capsid

Answer 3

protein shell surrounding virus

Question 4

what is a nucelocaspid

Answer 4

inner structure of protein + nucleic acid

Question 5

what is an envelope

Answer 5

phospholipid bilayer (derived from host) + proteins

Question 6

what is a lytic

Answer 6

viral infection that kills the host cell

Question 7

what is lysogenic

Answer 7

viral infection where the virus genome integrates into host genome

Question 8

name 4 ways virus’ spread

Answer 8

skin bites

blood transfusions

mucous membranes

breast milk

Question 9

name 3 spreading ability factors

Answer 9

viability in environment

ability to survive in host

resistance to bodily sites

Question 10

describe a naked virus

Answer 10

They lack n external membrane

Question 11

described and envelope virus

Answer 11

has additional lipid coat derived from the host

Question 12

give 2 examples of a naked virus

Answer 12

rhinovirus

poliovirus

Question 13

enveloped virus examples

Answer 13

influenza

HIV

Question 14

describe structure of virus

Answer 14

extremely small

contain few proteins in capsid

precise ordres

cannot be seen with convention microscope

Question 15

how are viruses classified?

Answer 15

based on symmetry

Question 16

what are the three classifications for viruses?

Answer 16

• helical
• icosahedral
• complex

Question 17

how do we identify helical viruses?

Answer 17

length of nucleic acid

Question 18

what do icosahedral viruses have

Answer 18

20 faces and 12 vertices

requires smallest number of capsomeres to build it

Question 19

viruses can be complex structures with…

Answer 19

each part having own structure and symmetry

Question 20

example of helical virus

Answer 20

tobacco mosaic virus

Question 21

example of icosahedral

Answer 21

human papilloma virus

Question 22

example of complex virus

Answer 22

bacteriophage T4

Question 23

what protein do envelopes usually have and what does it do

Answer 23

spike protein

binds to and enter cells

Question 24

how do viruses exit cells

Answer 24

budding

where they take a part of the host Plasma membrane with them

or cell lysis

Question 25

what can classification of nucleic acid be

Answer 25

rna or dna single or double stranded

Question 26

example of RNA virus

Answer 26

HIV

Question 27

example of a DNA virus

Answer 27

Hepatitis B

Question 28

what can single stranded viruses be

Answer 28

plus minus

Question 29

what direction do plus stranded run in

Answer 29

5' to 3'

Question 30

what direction do minus stranded run in

Answer 30

3' to 5'

Question 31

what is plus and minus stranded also referred to

Answer 31

positive and negative sense

Question 32

can DNA be transcribed immediately?

Answer 32

yes

Question 33

what are the 7 categories of the Baltimore classification system/

Answer 33

double-stranded DNA viruses (Group I) single-stranded DNA viruses (Group II) double-stranded RNA viruses (Group III) positive single-stranded RNA viruses (Group IV) negative single-stranded RNA viruses (Group V) positive single-stranded RNA viruses (Group VI) positive double stranded DNA viruses (Group VII)

Question 34

what do positive sense RNA genomes have

Answer 34

cap at 5' end and poly A tail at 3' end used directly as mRNA

Question 35

describe negative sense RNA genomes

Answer 35

first using a virus encoded RNA polymerase a positive sense RNA is made this is then capped and polyadenylated used directly as mRNA

Question 36

can viruses metabolise?

Answer 36

no

Question 37

what is an example of a key enzyme important for virus life cycle?

Answer 37

neuraminidase

Question 38

name the stages for virions to be released

Answer 38

1. attachment 2. penetration 3. nucleic acid and protein synthesis 4. capsid assembly and genome packaging 5. vision release

Question 39

what is attachment

Answer 39

when the virus binds to the cell

Question 40

what is penetration

Answer 40

injection of viral nucleic acid into host cell

Question 41

what is nucleic acid and protein synthesis driven by

Answer 41

host under viral control

Question 42

where does vision release occur

Answer 42

at the cell membrane in multiple ways

Question 43

name the 4 growth phases of the viral life cycle

Answer 43

eclipse phase maturation phase

Question 44

what happens at eclipse phase

Answer 44

viral genome and proteins replicated

Question 45

what happens at maturation phase

Answer 45

viral nucleic acid and mature viruses accumulate in cell

Question 46

what is burst size

Answer 46

number of released viruses

Question 47

what is burst size

Answer 47

number of released viruses

Question 48

what changes during a lysogenic infection in virion release

Answer 48

after penetration, nucleic acid integrates into the host genome and called a prophage cells divide and also replicate the viral genome

Question 49

what are the 5 stages of a typical human infection

Answer 49

1. binding and fusion endocytosis uncoating replication ,translation and transcription assembly and release

Question 50

what are 2 consequences of a virus infection?

Answer 50

The infection can be PERSISTENT and not kill the cell but cause continual viral release by budding e.g. HIV Some viruses can cause a normal cell to become cancerous and this is called TRANSFORMATION e.g. human papilloma virus

Question 51

what is a retrovirus?

Answer 51

a virus that has RNA instead of DNA as its genetic material

Question 52

which enzyme do retroviruses use

Answer 52

reverse transcriptase to become part of the host cells DNA

Question 53

what must retroviruses make during life cycle

Answer 53

a DNA intermediate