30 Questions
What is the diameter of the spherical enveloped particle of retroviruses?
~80-100nm
Which proteins are derived from the pol gene in retroviruses?
PR (protease), RT (reverse transcriptase), IN (integrase)
What is the function of the gag gene in retroviruses?
Production of group-specific antigen proteins: MA (matrix), CA (capsid), NC (nucleocapsid)
What is the initial step in the unique replication cycle of retroviruses?
Reverse transcription to produce a DNA copy of the RNA genome
What is the role of reverse transcriptase in retroviruses?
To produce a DNA copy of the RNA genome
Where does the DNA enter after being made from the ssRNA genome by viral enzyme integrase?
Nucleus with the viral enzyme integrase
What is bound to genomic RNA by base pairing with primer binding sequences downstream of U5?
A specific cellular tRNA
What are the two subfamilies into which retroviruses were reclassified?
Orthoretrovirinae and Spumaretrovirinae subfamilies
What is the function of Ppt in retroviruses?
It is used during reverse transcription
What is the main basis for the tropism of retroviruses?
Interaction of SU with cellular receptor
What is the role of ribonuclease H (RNAse H) in reverse transcription?
Specifically degrades the RNA part of the RNA:DNA hybrid
What facilitates the DNA polymerase activity during reverse transcription?
Virus-associated cellular tRNA
Which type of genome does HIV possess?
+ssRNA (positive sense single-stranded RNA)
What causes depletion of CD4+ T cells in HIV-infected individuals?
All of the above
What is the main basis for the tropism of retroviruses?
Interaction of SU with cellular receptor
What is the diameter of the spherical enveloped particle of retroviruses?
~100nm
What facilitates the DNA polymerase activity during reverse transcription?
Virus-associated cellular tRNA
What is the role of ribonuclease H (RNAse H) in reverse transcription?
Specifically degrades the RNA part of the RNA:DNA hybrid
What is bound to genomic RNA by base pairing with primer binding sequences downstream of U5?
Virus-associated cellular tRNA
Which proteins are derived from the pol gene in retroviruses?
Reverse transcriptase and integrase
What causes depletion of CD4+ T cells in HIV-infected individuals?
HIV replicating in and killing lymphocytes and macrophages
What is the function of Ppt in retroviruses?
Ppt is polypurine tract used during reverse transcription
What is the function of the env gene in retroviruses?
Codes for external surface protein and transmembrane protein
What is the role of the U3 region in retroviruses?
It is a splice site
What is the function of the protease (PR) protein in retroviruses?
Cleaves the polyprotein into mature proteins
What is the specific cellular component bound to genomic RNA by base pairing with primer binding sequences (PBS) downstream of U5?
Transfer RNA (tRNA)
What is the primary function of reverse transcriptase (RT) in retroviruses?
Catalyzes the synthesis of DNA from RNA template
What is the role of nucleocapsid protein in retroviruses?
Packages viral RNA genome with nucleic acid
What is the function of integrase (IN) enzyme in retroviruses?
Facilitates integration of viral DNA into host cell DNA
Which proteins are derived from the gag gene in retroviruses?
Matrix, Capsid, Nucleocapsid proteins
Test your knowledge about retroviruses and the process of reverse transcription with this quiz. Discover more about the structure, function, and classification of these unique RNA viruses.
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