Viral biology

Question 1

what is a virus

Answer 1

‘DNA or RNA that is protected by a protein coat

Question 2

size

Answer 2

25-300nm in size

Question 3

consists of

Answer 3

RNA, DNA or both

–> double or single stranded

Question 4

extracellular form

Answer 4

vision- protein encapsulated DNA or RNA

Question 5

intracellular form

Answer 5

replication of DNA/RNA and proteins; assembly of virus

Question 6

bacteriophages

Answer 6

virus which infects bacteria

Question 7

mycophages

Answer 7

virus which infection animals, plants and fungi

Question 8

virus’ are not

Answer 8

CELLS

Question 9

virus particles

Answer 9

self -assemble

Question 10

structure of a virus

Answer 10

protein coat which contains a few proteins that self assemble

Question 11

proteins inside a virus known as

Answer 11

capsomers

Question 12

protein coat known as

Answer 12

capsids

Question 13

capsids

Answer 13

protect RNA/DNA of virus

Question 14

virus’ can be ..

Answer 14

helical or icosahedral– determined by capsid

Question 15

organisation of the virus particles

Answer 15

naked virus–> enveloped virus –>complex virus

Question 16

naked virus

Answer 16

• capsid
• nucleic acid (DNA or RNA)
• enzymes (lysosomes, reverse transcriptase)

Question 17

enveloped virus

Answer 17

• capsid
• nucleic acid
• enzymes
• biomembranes- lipids from the host cell
• enveloped proteins (from virus)

Question 18

complex virus

Answer 18

• capsid
• nucleic acid
• enzymes
• complex protein tail

Question 19

example of an enveloped virus

Answer 19

• HIV- causes acquired immunodeficiency syndrome

- influenza

Question 20

example of a complex virus

Answer 20

T4 phage

Question 21

three ways in which virus’ enter a host cell

Answer 21

1) endocytosis
2) membrane fusion
3) injection

Question 22

endocytosis

Answer 22

the virus triggers clathrin-mediated endocytosis and enters the cell as a “trojan horse”

Question 23

membrane fusion

Answer 23

enveloped virus particles bind to receptors in the plasma membrane of host and forces membrane fusion

Question 24

injection

Answer 24

bacteriophages inject their genetic info and leave the rest of the virus particle behind

Question 25

virus particles can

Answer 25

move within infected cells

Question 26

how do virus' move within cells

Answer 26

- dependent on dynein | - virus particles move along microtubules

Question 27

viral particles move along

Answer 27

microtubules

Question 28

viral replication requires

Answer 28

microtubules and F-actin

Question 29

bi-directional motility

Answer 29

at around 2.5 um/s

Question 30

spreading of released virus'

Answer 30

-smaller droplets can remain airborne for hours or even days

Question 31

in public envionment

Answer 31

16,000 viruses/ cubic metre of air

Question 32

release of an enveloped virus

Answer 32

1) transcription of viral RNA/DNA 2) translation 3) assembly 4) budding at C>S>M 5) release

Question 33

life cycle of an enveloped virus

Answer 33

1) enveloped virus fuses with the membrane 2) enveloped into a clathrin pit in the cell and move towards the nucleus via molecular motors and microtubules 3) enveloped virus then releases content 4) nucleic acid goes into the nucleus and is replicated, transcribed and translated 5) new virus' form which are then exocytosed from the cell- this process enveloped the virus

Question 34

life cycle of a bacteriophae

Answer 34

1) virus attaches to the surface receptors 2) tails contracts, lytic enzymes break the wall and the core needle pinches the cell 3) the content of the head (proteins, DNA/RNA) is released into the cell 4) bacterial metabolism is disrupted and the genomic DNA degraded 5) Viral DNA is replicated and viral DNA is transcribed into mRNA- 6) mRNA is translated into viral proteins - complex virus particle self-assembles inside the host 7) 50-100 phages assemble in infected cell - lytic proteins (lysosomes) disintegrate the cell and release the phages

Question 35

T4 bacteriophage

Answer 35

- conists of 25 structural proteins nd double stranded DNA | - injection apparatus

Question 36

which proteins cause apoptosis of virus

Answer 36

lysosomes disintegrates the cell and releases the phages