8.1 - intro into viruses

Question 1

what are virusus

Answer 1

obligate intracellular parasites

-

Question 2

where can the viral replication occur once it has infected the body

Answer 2

within the host cell - because it has the machinery for it

Question 3

what do virus exist as

Answer 3

extracellular virion containing DNA or RNA virus genome or nucelic acid

Question 4

shapes of a virus

Answer 4

spherical containing

capsid with viral DNA and proteins in it

Question 5

classification of viruses

Answer 5

RNA or DNA

• segmented or non segmented
• single stranded (ssRNA + or -) or double stranded (dsRNA)

Question 6

what is the difference between segmented and non segmented virus

Answer 6

segmented > genomes divided into two or more segments and packaged
non > single segment packaged into single particle

Question 7

what is +ssRNA

Answer 7

can be translated straight away

-like mRNA

Question 8

what is -ssRNA

Answer 8

complementary to mRNA so has to make a another complemetary RNA by RNA ploymerase so it can be translated

Question 9

virus lifecycle

Answer 9

1. Adsorption (ait on the host cell)
2. Entry into the cell
3. replication including protein synthesis of viral DNA from capsid
4. virus release

Question 10

steps in virus entry to target cells

Answer 10

1. encounters the cell
2. binds to specific receptors on the surface
3. entry into cells and release of genome

Question 11

what is needed so the virus can enter

Answer 11

cell surface receptors so virus can bind to and enter

Question 12

different ways that the virus can enetr

Answer 12

endocytosis or fusion

Question 13

how does naked virus entry work and example of the virus who uses this pathway

Answer 13

poliovirus

• has antigens that forms a cleft that is specific to a host receptor
• binding cause conformational change
• VP 1 proteins inserted into the host plasma membrane and forms a pore
• RNA releases into the host cell

Question 14

how does enveloped virus entry work and an example of it

Answer 14

EBV into B cells

• antigen (gp350) binds to a receptor
• activates few proteins > conformtional change
• gB triggered and inserted into the membrane
• triggers fusion

Question 15

how many classes of viruses do you have

Answer 15

7

Question 16

what do ssDNA need to do to make proteins

Answer 16

• replicated to become ds using DNA polymerase from host cell
• transcipted to make mRNA using RNA polymerase from host
• translated

Question 17

what do dsDNA need to do to make proteins

Answer 17

• transcipted to make mRNA using RNA polymerase from host

- translated

Question 18

what do +ssRNA need to do to make proteins

Answer 18

translated straight away

mRNA is +

Question 19

what do -ssRNA need to do to make proteins

Answer 19

• need to use RNA polymerase from virion (RNA dependent RNA polyermase - RdRp)
• RdRp brought into the cell

Question 20

diff between viral DNA and Viral RNA

Answer 20

DNA > stable, long lasting, less error during DNA replication
RNA > the opposite