Cell Biology Questions and Answers – Gene Expression – Messenger RNA

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This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Gene Expression – Messenger RNA”.

1. When were the first structures of ribosomal subunits made by scientists?
a) 1980
b) 1990
c) 2000
d) 2010
View Answer

Answer: c
Explanation: The first structures of ribosomal subunits were made in the year 2000 by scientists Venkatraman Ramakrishnan, Thomas A. Steitz and Ada E. Yonath, which is available in the Protein Data Bank.
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2. The “S” in the 80S ribosomes stands for _______________
a) Svedberg’s units
b) Sedimentation coefficient
c) Sulphur-labeled
d) Supersonic
View Answer

Answer: a
Explanation: “S” stands for Svedbergs, a measure of how fast the molecule moves in a centrifuge. The rate of sedimentation is related to the shape and size of the molecule.

3. Which of the following are precursors for mRNAs?
a) snoRNA
b) hnRNA
c) siRNA
d) tRNA
View Answer

Answer: b
Explanation: Heterogeneous nuclear RNAs (hnRNA) are large molecular weight RNA molecules, present exclusively in the nucleus. They are precursors to the cytoplasmic mRNAs.

4. Which of the following has the smallest half life?
a) hnRNA
b) mRNA
c) tRNA
d) siRNA
View Answer

Answer: a
Explanation: Heterogeneous nuclear RNA (hnRNA) has the smallest half, it is processed into mRNAs shortly after or even during synthesis.

5. All mRNA precursors are synthesized by ___________________
a) RNA polymerase I
b) RNA polymerase II
c) RNA polymerase III
d) RNA polymerase IV
View Answer

Answer: b
Explanation: All eukaryotic mRNA precursors are synthesized by RNA polymerase II, it is conserved from yeast to mammals.
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6. Which of the following gene encodes for the white of a chicken egg?
a) ovalbumin
b) globulin
c) troponin
d) dystrophin
View Answer

Answer: a
Explanation: The gene that codes for the white of a chicken is ovalbumin. The promoter of this gene is located between 24 and 32 bases upstream in the region called TATA box.

7. TFIID is a ______________
a) protein complex
b) transcription factor
c) endonuclease
d) ribonuclease
View Answer

Answer: a
Explanation: Transcription factor for polymerase II, fraction D (TFIID) is a protein complex whose subunit is TATA-binding protein (TBP). Its function is to initiate accurate transcription of the mRNA.

8. Which enzyme unwinds the DNA?
a) helicase
b) topoisomerase
c) nuclease
d) endonuclease
View Answer

Answer: a
Explanation: The enzymes that unwind the DNA are known as DNA helicases. Unwinding of DNA enables the access of polymerase.

9. More than one RNA polymerase can attach to the promoter site.
a) True
b) False
View Answer

Answer: a
Explanation: For as long as a transcription factor for polymerase II, fraction D (TFIID), remains bound to the promoter additional RNA polymerase molecules are able to attach.
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10. The RNA polymerase engaged in transcription is ________________
a) acidic
b) alkaline
c) phosphorylated
d) non-phosphorylated
View Answer

Answer: c
Explanation: The RNA polymerase engaged in transcription is heavily phosphorylated while the same enzyme assembled into the pre-initiation complex (PIC) is not phosphorylated.

11. Messenger RNAs are found in the ________________
a) nucleus
b) cytoplasm
c) nucleolus
d) lysosome
View Answer

Answer: b
Explanation: Messenger RNAs (mRNAs) are present in the cytoplasm and are attached to ribosomes where they are translated.

12. Eukaryotic mRNAs have special modifications, not present in prokaryotic mRNAs.
a) True
b) False
View Answer

Answer: a
Explanation: Eukaryotic mRNAs have special modifications on 5’ and 3’ termini, which are not present in prokaryotic mRNAs or on rRNAs or tRNAs. These include poly(A) tail on 3’ end and methylated guanosine cap on 5’ end.

13. Genes with intervening (non-coding) sequences are called ___________________
a) axons
b) exons
c) split genes
d) jumping genes
View Answer

Answer: c
Explanation: The genes with intervening, non-coding regions are called spit-genes. The coding part is called exon and non-coding part is called intron.
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14. Which technique was used to find the relationship between 15S and 10S globin RNAs?
a) S-loop formation
b) R-loop formation
c) Pulsed-field gel electrophoresis
d) Polymerase chain reaction
View Answer

Answer: b
Explanation: The technique known as R-loop formation was employed by Shirley Tilghman, Philip Leder, and their co-workers at the National Institutes of Health for discerning the relationship between 15S and 10S globin RNAs.

15. Which of the following prevents the digestion of mRNA by exonucleases?
a) methyl-guanosine cap
b) methylene blue
c) poly(A) tail
d) bromophenol blue
View Answer

Answer: a
Explanation: The methylguanosine cap at the 5’ end of the mRNA prevents its digestion by the exonucleases and also plays an important role in the initiation of translation.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn