E. coli takes 40 min. to duplicate its genome using a bi-directional mode of replication. If E. coli were to use uni-directional mode of replication to synthesize a full copy of DNA complementary to just one of the strands of the genome, it would take

• 40 min

• 80 min

• 20 min

• 60 min

Transcriptional regulation of trp operon by tryptophan inolves binding of tryptophan to 

• the repressor protein and inhibition of transcription by its interaction with the operator region.

• RNA polymerase and inhibition of transcription. 

•  The repressor protein leading to structural changes and its degradation by proteases. 

• the repressor protein leading to its interaction with the sigma subunit and inhibition of transcription. 

Phosphorylation of eIF2 a subunits (at Ser 5I) leads to 

• inactivation of Met-tRNA, binding activity of eIF2B.

• sequestration of eIF2B because of tight binding between eIF2 and eIF2B

•  degradation of eIF2B. 

• enhanced guanine exchange activity of eIF2B.

If a disease caused by an intracellular pathogen is associated with host anti-inflammatory response, which one of the following may lead to an effective therapeutic approach? 

• Treatment with TGF-b

• Treatment with macrophage activating agent

• Depletion of IFN-g from the system

• Treatment with IL-4 and IL-10 

85.

A researcher attempted to clone two genes (X and Y) independently in a plasmid vector for over expression and purification in E. coli. All attempts to clone gene X were unsuccessful whereas gene ‘Y’ could be cloned easily. When the researcher attempted to clone gene ‘X’ in the plasmid clone containing gene ‘Y’, gene ‘X’ could be cloned. The following statements were proposed to explain the above results.

 

(a) Protein encoded by gene ‘Y’ is not lethal to the cell.

 

(b) Gene ‘X’ has introns, which prevents its expression in E. coli.

 

(c) Expression of ‘X’ protein is lethal to the cell.

 

(d) The ‘Y’ gene product inhibits the activity of ‘X’ protein..

 

Which one of the following options represents a combination of correct statements to explain the observations?

• only (a) and (b)

• (b), (c) and (d)

•  only (a) and (d)

• (a), (c) and (d) 

In an attempt to increae the yield of a commerically important enzyme from natural isolate, several strateiges were adopted as follow:

(a) genome was selectively modified to increase yield.

(b) Reappraisal of culture requirements of the modified organism to increase yield.

(c) Induced mutants were screened and selected for organism synthesizing improved levels of the enzyme.

(d) Organism was genetically modified, so that it produces a factor that enchances stability of the enzyme.

Which of the following options represents strategies that are appropriate for the purpose?

• (a), (b), (c) and (a)

• (b) and (c) only

• (a), (c) and (d) only

• (a) and (b) only

Given below are four statements related to Agrobacterium-mediated transfer of T-DNA into plants cells:

(a) Production of single-stranded T-DNA by VirD1 and VirD2 proteins.

(b) interaction of VirE2 with VIP1 and VirE3.

(c) Use of VirB/VirD4 type IV selection system.

(d) Activation of VirA-VirG complex.

The correct sequences of events ( from earlies to latest) is:

• (a)-(b)-(d)-(c)

• (b)-(c)-(a)-(d)

• (c)-(a)-(b)-(d)

• (d)-(a)-(c)-(b)

Using interrupted mating, four Hfr starin were analysed for the sequences in which they transimitted a number of different gene to a F^- strain. Each Hfr starin was found to transmit its genes in unique order as summarized in the table [ only the first five gene were scored].

Which one of the following correctly represents the gene sequences in the orginal strain from which the Hfr strains were derived as well as the place of intergration and polarity of the F plasmid?

Monoclonal antibodies can be modified for better research and therapeutic application. Several such approaches are mentioned below (column A) along with their possible applicatins (column B).

Column A	Column B
(a) Binding sites of the original mouse mAb are placed onto the Fe regions of human antibodies	(i)Abzyme
(b) Antibodies are modified by conjugation to toxin designed to kill cells to which the antibody will bind	(ii) Reduce side effect of xenogenic antibodies in immunotherapy
(c) Generation of mAb that specifically bind and stabilize the transition state of a chemical reaction	(iii) Immunotoxins

Which one of the following options represents a correct combination of term in Column A and Column B?

• (i)

  (ii)

  (iii)

• (ii)

  (i)

  (iii)

• (iii)

  (ii)

  (i)

• (ii)

  (iii)

  (i)

Viruses adopt different strategies to supress immune response of the host. Which one of the following statements is NOT correct?

• Human Immunodeficiency Virus (HIV) destroys CD4⁺T cells

• Epstein-Barr Virus (EBV) produces a homolog of human IL-10.

• Human influenza virus directly infects CD8⁺T cells

• Human Cytomegalo Virus (CMV) establishes latent infection in bone marrow stem cells