CSIR Biochemistry MCQ question part - 4

31. The factor required only for accurate initiations of transcription in prokaryotes is
(a) alpha (a) (b) beta (b)
(c) rho (r) (d) sigma (s)

32. A post-transcriptional processing event that occurs in the formation of both messenger
RNA (mRNA)and transfer RNA (t-RNA) in eukaryotes is
(a) the addition of the sequence CCA to 3′ ends
(b) the removal of introns by splicing
(c) the modification of some of their bases
(d) cleavage event before polyadenylation

33. Eukaryotic mRNAs differ from Prokaryotic mRNAs in that
(a) they do not have a 5′ untranslated region
(b) their coding regions are separated by spacers
(c) they do not have 3′ UTR
(d) they have a free 3′ hydroxy group on each of their ends

34. Degeneracy of the genetic code means that
(a) a given base triplet can code for more than one amino acid
(b) there is no punctuation in the code sequence
(c) the third base in a codon is net important for coding
(d) a given amino acid can be coded for by more than one base triplet

35. Which one of the following sequences is most likely to be a restriction enzyme
recognition site?
(a) CGGC (b) CGC

36. Which step is the first in the formation of a double stranded complementary DNA
(c DNA) target for cloning?
(a) blunt end ligation
(b) DNA dependent DNA synthesis
(c) Restriction enzyme cleavage
(d) Primer annealing

37. Cyclic AMP regulates the lactose (lac)operon by
(a) binding to the operator to turn on transcription
(b) binding to the lac repressor to prevent transcription
(c) combining with the catabolitic activator protein (CAP) to form a complex that
enhances transcriptions upon binding to the promotor .
(d) combining with the CAP to remove CAP’s inhibition of transcription

38. A 4 Kb covalently closed circular (ccc) plasmid has 2 (two) sites for a restriction enzyme
1 kb apart. It is partially digested by the enzyme. The maximum number of bands
that could be seen on a gel will be
(a) 1 (b) 2
(c) 3 (d) 4

39. In an enzyme reaction the reaction velocity becomes more than double when the
substrate concentration is doubled. This is possible when the equation governing the
kinetics is
(a) Michelis-Menton Kinetics
(b) Micheils-Menton Kinetics with substrate inhibition
(c) Michelis-Menton Kinetics with product inhibition
(d) Hill Equation

40. A mixture separated on HPLC gives clearly defined peaks whereas in a manually run
column the peaks tend to blend into each other. This is primarily because
(a) the small size of the packing material used in the HPLC column
(b) the better control of flow in HPLC
(c) the use of high pressure in HPLC
(d) the use of better detection systems in HPLC

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