Cancer Biology MCQ – Set 5

This set of Cancer Biology Multiple Choice Questions & Answers (MCQs) focuses on “Micro RNAs (miRNAs)”.

1. What is the length of miRNA?
a) 10-15 bp
b) 18-24bp
c) 1-5bp
d) 26-40bp
View Answer

Answer: b
Explanation: miRNA are the short non coding RNA that are complementary to the messenger RNA. The length of microRNA or miRNA is just 18-24 bases in length.

2. What of the following is incorrect for microRNA?
a) miRNA are exogenous
b) miRNA can base pair with complementary mRNA sequence
c) miRNA are endogenous
d) miRNA are typically of 18-24 bp in length
View Answer

Answer: a
Explanation: miRNA are endogenous short non coding RNA which are typically of 18-24 bp in length. They can base pair with complementary mRNA sequence in the same way as DNA base pairs in double helix.

3. What is the alternate name for DGCR8?
a) Dicer
b) DROSHA
c) Oncomir
d) PASHA
View Answer

Answer:
Explanation: DGCR8 is a microprocessor subunit complex. The protein is also called as PASHA in Drosophila melanogaster and Caenorhabditis elegans. The protein is an essential component for RNA interference pathway.
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4. How many types of human miRNA are there?
a) 500
b) 600
c) 1000
d) 800
View Answer

Answer: d
Explanation: The regulation of apoptosis, proliferation and cellular differentiation involves atleast 800 human miRNA. It is often seen that level of miRNA is low in tumours which shows that when switched on it provides protection against development of tumours

5. Which of the following sequence is correct for miRNA synthesis?
a) Pri-miRNA is processed to pre-miRNA in nucleus
b) miRNA is generated by Drosha and Dicer.
c) pri-miRNA is processed to pre-miRNA in cytoplasm
d) After being generated, miRNA incorporates into RISC
View Answer

Answer: c
Explanation: Pri-miRNA is processed into pre-miRNA in nucleus. miRNA is generated by two proteins called Drosha and Dicer. After generation of miRNA, one of its strand incorporates into RNA induced silencing complex. MiRNA directs RISC to inhibit translation or degrade RNA.

6. Which mRNA target CDK4 and BCL2?
a) mir-34
b) mir-4
c) mir-21
d) lin-2
View Answer

Answer: a
Explanation: Micro RNA (mir-34) is switched on by p53. It has two mRNA targets CDK4 and BCL2. CDK4 synthesis blockage leads to cell cycle arrest. Whereas, BCL2 is an anti-apoptotic protein, thus preventing its synthesis leads to apoptosis.

7. Which of the following stands corrects for differentiation between siRNA and miRNA?
a) siRNA is not conserved throughout the species while miRNA are highly conserved in the related organisms of species
b) miRNA and siRNA are endogenous RNA
c) siRNA and miRNA are double stranded RNA
d) miRNA and siRNA both have single duplex structure
View Answer

Answer: a
Explanation: miRNA are endogenous single stranded RNA whereas siRNA are exogenous double stranded RNA. Also miRNA has heteroduplex structure while siRNA has single duplex structure.

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8. Which of the following does not stands corrects for similarity between siRNA and miRNA?
a) miRNA and siRNA are short noncoding RNA.
b) siRNA and miRNA are found in all animals and plants.
c) miRNA and siRNA are novel classes of therapeutic agents which are used to treat cancers as well as infections.
d) siRNA and miRNA both are duplex RNA molecules.
View AnswerAnswer: b
Explaination: siRNA is not found in mammals. It is however present in lower animal as well as plant kingdoms. Whereas, miRNA are present in all animals and plants.

9. Which of the following miRNA act as tumor suppressor?
a) mir-10b
b) mir-155
c) mir17-92
d) mir-21
View Answer

Answer: a
Explanation: mir-10b is down-regulated in breast cancer, thus it acts as tumour suppressor. Whereas, mir17-92 gene locus is oncogenic as it is overexpressed in B cell lymphoma. Mir-21 and mir-155 acts as oncogene in breast cancer.
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10. What was the first miRNA to be discovered?
a) mir-34
b) lin-4
c) mir-21
d) lin-2
View Answer

Answer: b
Explanation: Ambros and colleagues discovered first miRNA, lin-4. It was discovered as small non-protein-coding RNA in Caenorhabditis elegans (C.elegans) which affected development by regulating expression of protein lin-14.

11. What was the first the first human disease associated with deregulation of miRNA?
a) T cell lymphoma
b) Sarcoma
c) B cell chronic lymphocytic leukaemia
d) B cell acute lymphocytic leukaemia
View Answer

Answer: c
Explanation: B-cell chronic lymphocytic leukemia was the first human disease found due to deregulation of two miRNA genes, mir-15a and mir-16-1. Chromosome 13q14 region was frequently deleted in these cancer which actually contains these two micro RNA.

12. Which was the first miRNA gene to be discovered as oncomir?
a) mir-15a/16-1
b) mir-14
c) mir-21
d) mir-31/mir15a
View Answer

Answer: a
Explanation: mir-15a/mir16-1 cluster gene was the first miRNA gene location to be observed as oncomir. Its loss at chromosome 13q14 was observed in B-cell chronic lymphocytic leukaemia.

13. Which of the following stands incorrect for Drosha or Dicer?
a) Drosha and Dicer are endonuclease
b) Drosha and Dicer are RNAse III
c) They are responsible for formation of miRNA and pre-miRNA duplex
d) Drosha and Dicer are RNAse II
View Answer

Answer: d
Explanation: Pre miRNA and miRNA duplex are formed by Drosha and Dicer. They are RNAse III endonucleases in miRNA maturation. Both of these enzymes are deregulated in certain tumours.

14. Which micro RNA is responsible for down regulation of tumor suppressor PDCD4?
a) mir-34
b) mir-569
c) mir-21
d) mir-15a
View Answer

Answer: c
Explanation: mir-21 is an oncomir which promotes cancer’s invasion and metastasis by down regulating tumour suppressor PDCD4. It is abundant in human cancer such as cervical, thyroid, breast, colorectal cancers etc.

15. Which micro RNA is responsible for down regulation of tumor suppressor TP53INP1?
a) mir-21
b) mir-143
c) mir-569
d) mir-145
View Answer

Answer: c
Explanation: Tumour metastasis and cell proliferation were seen as mir-569 of TP53INP1-a tumours suppressor gene was inhibited. TP53INP1 occurs at lower levels in more invasive cancers as compared to normal tissues likely due to mir-569.

Sanfoundry Global Education & Learning Series – Cancer Biology.

To practice all areas of Cancer Biology, here is complete set of Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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