Question

1. Calculate the multiplicity of infection if the probability of infection is 50%?

A) 10%

B) 0.693%

C) 5%

D) 6.93%

2. Which of the following is true concerning the viral envelope?

A) All viruses possess an envelope

B) The envelope may be cut apart by action of nucleases

C) The viral envelope is derived from various cellular membranes

D) The viral envelope is taken from the mitochondrial membranes

3. When infecting with a +sRNA virus, the genomic mRNA is translated into a polyprotein which

A) Needs the presence of reticulocyte translation system

B) Gets processed by protease

C) Gets inhibited by Actinomycin D

D) Codes for the rest of the needed translation machinery

4. Viruses whose genome is a polycistronic mRNA will need the polyprotein to be processed by

A) both, host cell protease followed by viral protease

B) Viral protease

C) Exogenous protease

D) Host cell Protease

Answer 1

1) d)6.93%

Explanation- To find m for a given probability of infection we use p(n>0)= 1- (m. e^-m))0!. So we get p= 1-e^-m, Which give m= -ln(0.5)= 0.693 mutilipying it by 100 gives 6.93%.

2) c) viral envelope is obtained from cellular membrane material.

Explanation- viruses takes their envelope by getting surrounded by cellular membrane that can be of cell itself or organelle of cell.

3) d) codes the rest of the translation mechinary.

Explanation - viruses contain genes of enzymes and factor required for their gene translation and replication for rapid dublication in host.

4) d)Host cell protease

Explanation- regulation of viral polycistronic mRNA is carried by host enzymes, their translation, viral structural, regulatory and all.