Scientists usually find difficulty in identifying the exact transcription termination site in eukaryotes because

• immediately following termination of transcription, the 3' end is polyadenylated.

• the 3' end is generated by cleavage prior to actual termination of transcription

• poly A binding proteins present at 3' end of transcript hides the termination site.

• 3' end of transcript is complexed with 5' end for initiation of translation.

In eukaryotic replication, priming of DNA synthesis and removal of RNA primer is catalyzed by

• DNA Pol α and PCNA, respectively

• DNA Pol α and PEN1, respectively

• DNA Pol δ and PEN 1, respectively.

• DNA Pol ε and PCNA, respectively

Which one of the following is NOT formed after post-translational processing of pre-glucagon?

• Glicentin

• β-lipoprotein

• Major proglucagon fragment

• Oxyntomodulin

In the following diagram, segments A and C are copies of 10 basepair repeat DNA sequences, flanking a unique stretch shown as B. A, and C are in inverted orientation as indicated by arrows. Intramolecular recombination between A and C leads to which event:

• The complete region encompasing A to C will be inverted.

• Only A and B will be inverted.

• Only B will be inverted

• Only regions A and C will be inverted

Two experiments were performed. In the first one, Okazaki fragments were prepared from a replicating cell of E. coli grown in the presence of ³²P. In the other, the two strands of E. coli chromosome were separated into a H strand and L strand, immobilized onto a nitrocellulose membrane and hybridized with the Okazaki fragments prepared in the first experiment.

Which one of the following options correctly describes the observation?

• Okazaki fragments will hybridize to only H strand.

• Okazaki fragments will hybridize to only L strand.

• Okazaki fragments will hybridize with both H and L strands.

• Because the H and L strands have been prepared from different cultures of E. coli, the Okazaki fragments will hybridize to neither.

Eukaryotic mRNAs have an enzymatic appended cap structure consisting of a 7-methylguanosine residue to the initial 5'-nucleotide of the transcripts. Given below are a few statements regarding capping.

A. Capping protects the mRNA from degradation by 5'-exoribonucleases.

B. During capping, the α-phosphate is released from the 5'-end of the nascent mRNA.

C. Phosphorylation mediated conformational change in carboxyl terminal domain (CTD) of RNA Pol II enables its binding with capping enzymes.

D. During capping, a 5'-5' triphosphate bond is formed between the β-phosphate of the nascent mRNA and α-phosphate of GTP.

Which of the above statements is/are INCORRECT?

• C only

• B only

• A and B

• C and D

127.

Injection of Noggin mRNA in cells that will become the future ventral side of a frog embryo mimics the effect of an organizer graft to the ventral side.This experiment demonstrates that

A. Noggin is a transcription factor.

B. Noggin induces ventral fates.

C. Noggin is involved in organizer fate.

D. Noggin is required to induce secondary axis.

Which one of the following options represents correct combination of statement(s)?

• A and C

• C and D

• A and B

• B and C

Which one of the following λ proteins acts both as an activator and repressor of transcription?

• cI protein

• N protein

• cII protein

• Q protein

A highly specific inhibitor that targets the phosphorylation activity of TFIIH is added to an in vitro transcription reaction. Which one of the following steps is most likely to be affected?

• Binding of RNA Polymerase to promoter sequence.

• Promoter clearance

• Recruitment of TFIID

• Open promoter complex formation

During eukaryotic protein synthesis, stress conditions result in activation of specific kinases leading to phosphorylation of a key translation initiation factor that inhibits protein synthesis from a large number of cellular mRNA. Which one of the following factors is the target of the kinase?

• eIF4E

• eIF4G

• eIF2α

• Gcn4