Molecular Biology: Protein Synthesis (Translation) & Lac Operon

Multiple Choice Question on 
Protein Synthesis and Regulations 

1) The genetic code is a triple nucleotide sequence in the mRNA that determines the amino acid sequence of the protein. Following are the characteristics of amino acid EXCEPT:
a) Specificity
b) Universal
c) Redundant
d) Overlapping

2) Aminoacyl t-RNA synthetase catalyzes the addition of amino acids to the growing polypeptide chain and it requires four high energy phosphates. They are
a) 4 ATP
b) 4 GTP
c) 2 ATP, 2 GTP
d) 1 ATP, 3 GTP

3) The ribosome has three binding sites (A, P, E) for tRNA molecules. Which of the following is NOT the correct statement regarding these sites?
a) The A site binds to an incoming aminoacyl-tRNA
b) The P site codon is occupied by peptidyl-tRNA (an amino acid containing tRNA)
c) The E site is occupied by empty t-RNA as it is exiting the ribosome
d) None of the Above

4) Shine Dalgarno sequence is located six to ten bases upstream of the initiation codon of mRNA. It consists of
a) Purine-rich nucleotide sequence
b) Pyrimidine rich nucleotide sequence
c) Uracil-containing nucleotide sequence
d) None of the above

5) Which of the following is the initiation codon?
a) UGA
b) AUG
c) CUA
d) GAA

6) In prokaryotes, the initiation factors (IF-1, IF-2, and IF-3) are involved in the initiation of protein synthesis. Which of the following factors facilitates the initiation codon?
a) IF-1
b) IF-2
c) IF-3
d) All of the above

7) EF-Tu and EF-Ts bind to appropriate tRNA to the codon in the empty sites. These factors are involved in the............ of translation.
a) Initiation
b) Elongation
c) Termination
d) Trimming

8) Chloramphenicol is a class of antibiotics that inhibit protein synthesis by inhibiting
a) Aminoacyl transferase
b) Peptidyl transferase
c) Initiation factor 1
d) Elongation factor

9) Puromycin, a structural analog of tRNA, is a class of antibiotics that inhibit protein synthesis by
a) inhibiting amino acyltransferase
b) inhibiting peptidyl transferase
c) early termination of the peptide chain
d) None of the above

10) Tetracyclin is a class of antibiotics that inhibit protein synthesis by blocking
a) binding of initiation factors
b) binding of elongation factors to tRNA
c) binding of aminoacyl tRNA to the mRNA-ribosome complex
d) None of the above


11) Which one of the followings is not true about genetic code?
a) It is degenerate
b) It is unambiguous
c) It is nearly universal
d) It is overlapping
12) Which of the following is not the component of ribosomal RNA present in prokaryotes?
a) 23S rRNA
b) 18S rRNA
c) 16S rRNA
d) 5S rRNA



13) Which of the following is not the component of ribosomal RNA present in eukaryotes?
a) 28S rRNA
b) 18S rRNA
c) 16S rRNA
d) 5S rRNA

14) Which of the following is the site for attachment of amino acid in tRNA molecule?
a) 5' end
b) 3' end
c) anti-codon loop
d) None of the above

15) Lactose Operon is a set of lactose metabolizing gene that is co-coordinately expressed and regulated. The following is not the gene of lactose operon:
a) LacX
b) LacZ
c) LacY
d) LacA

16) Which of the following is not the positive regulator of Lac operon
a) Allolactose
b) Glucose
c) Lactose
d) cAMP

17) Which of the following is the FALSE statement of the Lactose operon
a) Lac Operon is activated when glucose is absent
b) Lac Operon is activated when lactose is present
c) Lac Operon is activated when glucose is absent and lactose is present
d) Lac Operon is activated when glucose is present and lactose is absent

18) Which of the following gene encodes for repressor protein of lac operon
a) LacI
b) LacZ
c) LacY
d) LacA

19) LacZ encodes for a protein
a) permease
b) beta-galactosidase
c) transacetylase
d) repressor protein

20) Adenylyl cyclase is an enzyme that is active in the absence of
a) Allolactose
b) Glucose
c) Lactose
d) cAMP

21) Peptidyl transferase enzyme is present in
a) Messenger RNA
b) Transfer RNA
c) Ribosomal RNA
d) Small Nuclear RNA



21) The following are the post-translational modifications that may be required for trafficking or the function of the proteins, except:
a) Hydroxylation
b) Glycosylation
c) Oxygenation
d) Phosphorylation

Multiple Choice Answers
1)- d) Overlapping
2)- c) 2 ATP, 2 GTP
3)- d) None of the Above
4)- a) Purine-rich nucleotide sequence
5)- b) AUG
6)- b) IF-2
7)- b) Elongation
8)-d) Elongation factor
9)-c) early termination of the peptide chain
10)-c) binding of amino acyl tRNA to the mRNA-ribosome complex 

11)-d) It is overlapping
12)-b) 18S rRNA
13)-c) 16S rRNA
14)-c) anti-codon loop
15)-a) LacX
16)-b) Glucose
17)-d) Lac Operon is activated when glucose is present and lactose is absent
18)-a) LacI
19)-b) beta-galactosidase
20)-b) Glucose

21)-c) Ribosomal RNA
22-c) Oxygenation

Comments

Recommended Contents