Reverse Transcription (7)

Question 1

What is Baltimore Class VI?

a. ssDNA is converted to mRNA via dsDNA. As shown by Parvovirus
b. +RNA is converted to –DNA before forming dsDNA and being transcribed. As shown by Retrovirus
c. –RNA is converted to –DNA before forming dsDNA and being transcribed. As shown by Hepadnavirus
d. dsRNA is converted to dsDNA before being transcribed. As shown by Reovirus

Answer 1

b. +RNA is converted to –DNA before forming dsDNA and being transcribed. As shown by Retrovirus

Question 2

What is false about translation of retroviral proteins?

a. A highly stable RNA structure stalls ribosomes at the U-rich slippery sequence in pol
b. The reading frame of Pol shifts back -1 and gag can be translated
c. Envelope glycoproteins and viral enzymes are expressed from spliced mRNA
d. Structural proteins and viral enzymes are expressed from a Gag-pol polyprotein before autocleavage

Answer 2

c. Envelope glycoproteins and viral enzymes are expressed from spliced mRNA

Question 3

What is false about the reverse transcription of viral genome RNA to proviral DNA?

a. Duplication of sequences in the middle of genome +ssRNA creates a LTR
b. The process is error prone (1 in every 10,000 nt)
c. Reverse transcriptase can switch between genomes to generate recombination and diversity
d. dsDNA LTRs are generated due to the duplication of +ssRNA end sequences

Answer 3

a. Duplication of sequences in the middle of genome +ssRNA creates a LTR

Question 4

• In retroviruses, pol encodes MA, NC and CA whilst gag encodes RT

Answer 4

. F

Question 5

• In retroviruses, the diploid RNA genome is capped and polyadenylated and the RNAs are loosely joined at the 5’ end with each binding a cell tRNA.

Answer 5

T