MCQ’s Based on Translation and Operon Concept for ICAR (SRF or JRF) /ASRB /CSIR NET/BET Exams #1

 

1. Promoter regions are nucleotide sequences that
   A) are involved in the initiation of transcription
   B) are involved in transcription termination
   C) contain the code for 1 mRNA molecule
   D) are important to the translation process
   Ans: A

2. Codons are composed of
   A) triplet sequences of nucleotide bases in mRNA
   B) triplet sequences of nucleotide bases in DNA
   C) triplet sequences of amino acids in polypeptide chains
   D) triplet sequences of deoxyribose sugars in DNA
   Ans: A

3. Which of the following is not true of RNA processing?
   A) Exons are cut out before mRNA leaves the nucleus
   B) Nucleotides may be added at both ends of the RNA
   C) Ribozymes may function in RNA splicing
   D) RNA splicing can be catalyzed by spliceosomes
   Ans: A

4. Which of the following is not true of a codon?
   A) It consists of three nucleotides
   B) It may code for the same amino acid as another codon
   C) It never codes for more than one amino acid
   D) It extends from one end of a tRNA molecule
   Ans: D

5. When does translation begin in prokaryotic cells?
   A) after a transcription initiation complex has been formed
   B) as soon as transcription has begun
   C) after the 5' caps are converted to mRNA
   D) once the pre-mRNA has been converted to mRNA
   Ans: B

6. What is the most abundant type of RNA?
   A) mRNA
   B) tRNA
   C) rRNA
   D) pre-mRNA
   Ans: C

7. The first event in the translation is binding of mRNA to
   A) small subunit of the ribosome
   B) large subunit of the ribosome
   C) polysomal core
   D) tRNA
   Ans: A

8. The signal to start translation is the initiator codon, usually the AUG, the codon for
   A) tyrosine
   B) methionine
   C) tryptophan
   D) leucine
   Ans: B

9. Out of 64 codons, how many code for amino acids?
   A) 20
   B) 22
   C) 43
   D) 61
   Ans: D

10. In prokaryotes, the ribosome binding site on mRNA is
    A) Hogness sequence
    B) TATA box
    C) Shine-Dalgarno sequence
    D) Pribnow box
    Ans: C

11. Which is the energy-rich compound used for initiation of translation?
    A) ATP
    B) GTP
    C) CTP
    D) AMP
    Ans: B

12. DNA methylation may be a significant mode of genetic regulation in eukaryotes. Methylation regulates gene activity by
    A) adding methyl groups to the cytosine of CG doublets in DNA
    B) altering RNA polymerase activity by methylation
    C) changing DNA-DNA hydrogen bonding
    D) methylation of glycine residues
    Ans: A

13. The trp operon is
    A) repressible and under negative control
    B) inducible and under negative control
    C) inducible and under positive control
    D) repressible and under positive control
    Ans: A

14. A mutation in the I gene of the lac operon directly affects
    A) β-galactosidase
    B) repressor
    C) promoter
    D) operator
    Ans: B

15. When tryptophan is present in the environment of E. coli, the tryptophan binds to the
    A) trp operon
    B) trp promoter
    C) trp repressor
    D) trp operator
    Ans: C

16. A lack of this nonprotein molecule would result in the inability of the cell to "turn off" genes
    A) corepressor
    B) inducer
    C) promoter
    D) repressor
    Ans: A

17. This binds to a site in the DNA far from the promoter to stimulate transcription
    A) enhancer
    B) activator
    C) promoter
    D) terminator
    Ans: A