This set of Molecular Biology Multiple Choice Questions & Answers (MCQs) focuses on “RNA Polymerase Knows Where to Stop”.
1. The most common signal for termination of transcription is self complementation.
Explanation: Yes, the most common signal for termination of transcription is self complementation. This self – complementation leads to the formation of a hairpin loop. It is also known as the Rho independent termination.
2. The stem of the hairpin loop of RNA consists mostly of _____________
a) A, T
b) G, C
c) A, G
d) C, T
Explanation: The stem of the hairpin loop of RNA consists mostly of G, C. This makes the structure more stable and thus facilitating proper termination.
3. The hairpin structure generated in the RNA is followed by a stretch of oligonucleotide complementary to the base ____________
Explanation: The RNA hairpin is followed by a sequence of many “U” residues. Thus the complementary stretch of nucleotides in the DNA strand is adenine or “A”.
4. A stretch of which nucleotide in the DNA acts as the termination signal?
a) Poly G
b) Poly C
c) Poly T
d) Poly A
Explanation: A hairpin loop followed by a stretch of oligo U nucleotides acts as the termination sequence. This subsequent stretch of the “U” residue pairs weakly to the “A” residues of the DNA thus favoring easy dissociation.
5. The rho protein has ____________ subunit.
Explanation: The rho protein is a hexameric protein containing 6 subunits. This protein is known to mediate transcription and is known as the Rho dependent transcription.
6. The rho proteins are ATP independent proteins.
Explanation: The rho protein is an ATP dependent protein. It uses the hydrolysis of ATP to terminate the transcription in the presence of a single stranded RNA.
7. The rho protein binds to the RNA recognizes special structure. It consists of ____________ nucleotides.
Explanation: The rho protein binds to the RNA recognizes special structure. It consists of 40 nucleotides. Rho moves along the nascent RNA towards the transcription complex and helps terminate the RNA synthesis.
8. The rut sites are rich in ____________ residues.
Explanation: The rut sites are special sequences used by the Rho protein to bind to terminate the RNA synthesis. These stretches of RNA do not fold into any secondary structure and is rich in “C” residues.
9. The rho protein can even bind within operons to terminate transcription.
Explanation: The Rho protein fails to bind to any transcript of RNA that is being translated. Thus rho protein cannot bind within operons to terminate transcription and binds beyond the operon or gene to terminate transcription.
Sanfoundry Global Education & Learning Series – Molecular Biology.
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