This set of Molecular Biology Multiple Choice Questions & Answers (MCQs) focuses on “RNA Viruses and Reverse Transcription”.
1. RNA genomes were first discovered in ___________ viruses.
a) Plant
b) Animal
c) Bacterial
d) Fungal
View Answer
Explanation: RNA genomes were first discovered in the plant Tobacco mosaic virus. The first direct proof that RNA acts as the genetic material was obtained in 1950s by experiments demonstrating that RNA purified from TMV could infect new host cells giving rise to progeny viruses.
2. The initial hypothesis of RNA provirus was proposed by __________ in 1960s.
a) David Baltimore
b) Howard Temin
c) Robert Gallo
d) David J. Griffiths
View Answer
Explanation: The initial hypothesis of RNA provirus was proposed by Howard Temin in 1960s. In his experiments he found that the RNA tumor viruses replicate via synthesis of DNA intermediates called DNA proviruses, thus leading to his hypothesis.
3. Reverse transcription is an important phenomenon for eukaryotic cells.
a) True
b) False
View Answer
Explanation: Reverse transcription is not restricted to retroviruses it also occurs in cells. For example, reverse transcription is essential for the replication of telomeres of eukaryotic chromosomes. Also reverse transcription is responsible for the transposition of sequences from one position to the other.
4. The virus on which the first experiment performed by Howard Temin was __________
a) Human Immunodeficiency Virus
b) T lymphatic Virus
c) Rous Sarcoma Virus
d) Human papiloma virus
View Answer
Explanation: Rous sarcoma virus (RSV) the first cancer causing virus to be described was of considerable interest as an experimental system for studying the molecular biology of cancer. Howard Temin began his research in this area when, as a graduate student in 1958, he developed the first assay for the transformation of normal cell to cancer cells in culture following infection with RSV.
5. The viral genome contains which of the following characteristic sequences?
a) LINE
b) SINE
c) Transposons
d) LTRs
View Answer
Explanation: The viral genome contains the characteristic sequence of long terminal repeats (LTRs), which are direct repeats of several hundred base pairs. Viral genes including genes for reverse transcriptase, integrase and structural proteins of the virus particle, are located between the LTRs.
6. The integration of viral DNA into the host DNA is promoted by the host integrase enzyme.
a) True
b) False
View Answer
Explanation: The viral DNA integrates into the host cell chromosome by a process that resembles the integration of DNA transposable elements. This integration is catalyzed by a viral integrase and occurs at many different target sequences of the host chromosome.
7. Which of the following is not a function of reverse transcriptase?
a) RNA dependent DNA polymerase
b) DNA dependent DNA polymerase
c) RNase H
d) Exonuclease
View Answer
Explanation: Reverse transcription has a high error rate due to no proofreading activity. Thus the reverse transcriptase that facilitates reverse transcription has no exonuclease activity.
8. Reverse transcription has a high error rate.
a) True
b) False
View Answer
Explanation: As the reverse transcriptase has no exonuclease activity thus, proofreading of the synthesized cDNA is not possible. This accounts to the high error rate of 1.7*10-4 of reverse transcription.
9. What will be the transcription product of 3’….AUCCGAGCUAAC….5’ by reverse transcriptase?
a) 3’….GTTAGCTCGGAT….5’
b) 3’….AUCCGAGGAUUG….5’
c) 5’….GTTAGCTCGGAT….3’
d) 5’….UAGGCUCGAUUG….3’
View Answer
Explanation: The reverse transcriptase facilitates reverse transcription from RNA to DNA. The given sequence in the question is of RNA as it consists of “U” instead of “T” thus the resulting cDNA sequence should be 3’….AUCCGAGCUAAC….5’5’….TAGGCTCGATTG….3’.
10. Reverse transcription is a very important tool in modern molecular biology techniques.
a) True
b) False
View Answer
Explanation: Reverse transcription is a vital role in modern molecular biology techniques. It is the mere foundation of building the cDNA libraries. The enzyme reverse transcriptase also plays an important role in the PCR technique known as RT – PCR. This process is also used in cloning, sequencing and other molecular analyses.
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