CSIR JRF NET Life Sciences June 2014 Part C (Question 71 – 95)

CSIR/JRF/NET: Life Sciences, June 2014 (I)
COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH (CSIR) & UGC
(Original Question Paper)
PART: C (Questions 71 – 95)
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(71). 10mM acetate buffer (pH 4.00) is diluted one million times with distilled water (pH 7.00). pH of this diluted buffer is:

a. 4.00
b. 7.04
c. 8.00
d. 6.96

(72). Consider the structure less oligopeptide R-G-P-S-T-K-M-P-E-Y-G-S-T-D-Q-S-N-W-H-F-R. the number of bonds that will be cleaved by trypsin and chymotrypsin treatments separately are:

a. 1, 2
b. 2, 2
c. 2, 3
d. 1, 3

(73). The internal energy of a gas increases by 1 J when it is compressed by a force of 1 Newton through 2 meters. The heat change of the system is:

a. 1 J
b. -1J
c. 2J
d. -2J

(74). ΔGo for the base pairing of oligonucleotides (n=5) at 300 K is -18 kJ mol-1. What would be the approximate value of the equilibrium constant K?

a. 100
b. 10
c. 1000
d. 1

(75). The reaction of glutamate and ammonia to glutamine and water has a value of +14 kJ mol-1 for ?Go . This is coupled with the ATP reaction (ATP + H2O ⇔ ADP + phosphate). The ΔGo for this reaction is -30 kJ mol-1. The ΔGo (kJ mol-1) for the coupled reaction Glutamate + NH3 + ATP ⇔ Glutamine + ADP + Phosphate under equilibrium condition is:

a. 16
b. -44
c. -16
d. 44

(76). A protein is composed of leucine, isoleucine, alanine, glycine, proline, one lysine, one arginine and two cysteine connected by a disulfide bond. Conformational analysis indicates that the protein has elements of helix and beta structure. The protein is most likely:

a. A non-specific protease.
b. Not an enzyme.
c. A lipase
d. A flippase

(77). You are studying a protein that inserts itself into a model membrane (liposomes) during a reconstitution process. The protein has N-terminal, 18 amino acid hydrophilic segment that is located on the outside of the membrane, a 19-amino acid hydrophobic trans-membrane segment flanked by negatively and positively charged amino acids, and a C-terminal domain that resides inside the lumen (as depicted below in the form of a cartoon)

lipid bilayer

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For proper reconstitution of the protein which of the following strategies will be appropriate?

a. Increase the number of negatively charged amino acids in the N terminal
b. Increase the number of positively charged amino acids in the C-terminal
c. Removal of positively charged amino acids from the C-terminal
d. Increase the length of hydrophobic segment

(78). 125I- labeled diaminofluorene (DAF) is a well-known photoactivable hydrophobic probe of plasma membrane integral protein. To determine the approximate length and number of hydrophobic domain in any integral membrane protein, a controlled experiment (following standard protocol) is carried out. In order to ascertain the aforesaid aspects indicate the correct combination of experimental protocols from the following choices:

a. Intact membrane was allowed to interact with DAF and unincorporated DAF measured.
b. Intact membrane was allowed to interact with DAF, lysed and total protein precipitated with TCA and amount of radioactivity incorporated in the total proteins in the TCA precipitated fraction measured.
c. Intact membrane was allowed to interact with DAF, then membrane was solubilized with detergent, digested with proteases (limited proteolysis) run on SDS-PAGE followed by autoradiography.
d. Intact membrane was allowed to interact with DAF followed by complete proteolysis, SDS-PAGE and finally autoradiography.

(79). The tetra-peptide “KDEL” is well known as a retrieval signal of several newly synthesized proteins. This process is mediated through specific receptor – KDEL interaction. Any single amino acid change in this tetra-peptide is not allowed in terms of its binding with its receptors and its subsequent retention in specific organelle whereas; secretory proteins are devoid of such tetra-peptide. Form this observation indicate the localization of the receptor of this tetrapeptide:

a. Plasma membrane
b. Golgi
c. Endoplasmic reticulum
d. Mitochondria

(80). Cyclins are the regulatory subunits and cyclin dependent kinases (CDKs) are the catalytic subunits. Following diagram represents the involvement of cyclins and CDKs in various stages of cell cycle:

cyclin and cyclin dependent protein

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If we knock down cyclin D in a cell by shRNA, which one of the following graphs correctly represents the level of CDK2 activity?

cyclin and cdk in cell cycle

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a. Graph 1
b. Graph 2
c. Graph 3
d. Graph 4

(81). Chromosome organization becomes clearer from a series of biochemical, electron microscopic and X-ray crystallographic studies. When interphase chromatin is isolated in low salt buffer and observed under EM, 11 nm bead on string organization is seen. Interphase chromatin directly observed under EM shows 30 nm fibre. When histones are depleted from metaphase chromosome and visualized under EM, it shows a huge number of large loops associated with scaffold. Following interpretations can be made from these:

A. 11 nm fibre is formed when nucleosomes are brought closer by scaffold.
B. 30 nm interphase chromatin is formed by ziz-zag organization of nucleosomes of 11 nm fibre.
C. 30 nm fibre makes a solenoid packing to form the metaphase chromosome
D. 30 nm fibre gets organized into loops due to SARs getting associated with scaffold proteins and coming closer.

The correct combination of interpretation is:

a. A and D
b. A and C
c. A and B
d. B and D

(82). To test whether bacteria with enhanced toluene derivative abilities could be created for cold environment, a TOL (toluene degrading) plasmid from a mesophilic bacterial strain was transferred by conjugation into a facultative phychrophile. The psychrophile was able to degrade salicylate (SAL) but not toluene. The recombinant strain carried the introduced TOL plasmid and its own SAL plasmid. The result as follows:
Identify A, B, C, X and Y

TOL plasmid and bacteria

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a. A. mesophile, B. psychrophile, C. transformant, X. Toluene, Y. Salicylate
b. A. mesophile, B. psychrophile, C. transformant, X. Salicylate, Y. Toluene
c. A. psychrophile, B. transformant, C. mesophile, X. Salicylate, Y. Toluene
d. A. transformant, B. psychrophile, C. mesophile, X. Toluene, Y. Salicylate

(83). Aminoacyl-tRNA synthases are very specific for aminoacylation of tRNAs with the correct cognate amino acids. However, there is a possibility of a mismatch between the tRNA and its cognate amino acid. This error is corrected by the inherent proof-reading activity of the aminoacyl-tRNA synthases. In case of two very similar amino acids, namely valine and isoleucine, isoleucyl-tRNA synthase employs the following possible approaches for an error-free aminoacylation.

A. It removes an incorrect amino acid by hydrolyzing the aminoacyl-AMP linkage following the first reaction step.
B. It is activated for proof-reading activity, leading to breakage of the bond between the wrong amino acid and tRNA.
C. It has an intrinsic ability to recognize the structural difference between amino acids leading to abortive elimination of the non-cognate amino acid.
D. It gets sequestrated in the second step with the wrong amino acid, and that freezes the aminoacylation process.

Which of the following combination is correct?

a. A and B
b. A and D
c. B and D
d. C and D

(84). Attenuation is a mechanism involved in the regulation of tryptophan operon in E. coli. When tryptophan levels are high in the cell, region 2 of the trpL is blocked from pairing with region 3. This allows the pairing of region 3 and 4 leading to the formation of a rho-independent terminator. What would be the structure of the trpL region in E. coli cells where protein synthesis has been inhibited?

a. Region 2 pairs with region 3 allowing transcription of the structural genes.
b. Region 1 and 2 will pair, allowing 3 and 4 to pair leading to attenuation.
c. There is no pairing in the trpL region and transcription of structural gene occurs.
d. Region 2 and 3 will pair leading to attenuation.

(85). MicroRNAs (miRNA) have recently been shown to play a significant role in the fine tuning of gene expression. Some miRNAs induce gene silencing by binding to mRNAs and inducing inhibition of translation. On the other hand, there are miRNAs that bind to mRNAs and activate their degradation. The following characteristics can be applicable to the miRNAs that inhibit mRNA translation:

A. miRNA is partially complementary to a region of target mRNA in the 3’UTR.
B. miRNA always base pairs with mRNA around a AU-rich sequence.
C. miRNA base pairs with mRNA through 6-7 nucleotides at its 5’ end referred to as “seed sequence” as well as few additional bases elsewhere.
D. miRNA is always partially complementary to the 5’UTR of the target mRNA.

Chose the correct option from the following:

a. A and B
b. A and C
c. C and D
d. A and D

(86). A 6.4 Kb plasmid DNA has two restriction endonuclease sites, Hind III and EcoRI. Complete double digestion of the plasmid with both the enzymes yields two fragments of 3.1 and 3.3 Kb. In ourder to study DNA repair process, a G:T mismatch was introduced in one strand of HindIII site and the damaged plasmid was incubated in a reconstituted repair system containing all the factors and enzymes required for repair. If the efficiency of the repair system is 50%, which one of the following band patterns on agarose gel will be obtained after treating the repaired plasmid with both HindIII and EcoRI?

restriction endonucleases

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(87). The following statements are made on DNA replication:

A. Replication fork is branch point in a replication ‘eye’ or ‘bubble’.
B. A replication bubble contains two replication forks.
C. DNA replication is continuous according to the interpretation made by Okazaki.
D. Multiple priming events are required for both leading and lagging strands to initiate DNA synthesis.

Which one of the following is the correct combination?

a. A and B
b. B and C
c. C and D
d. A and C

(88). In order to identify the regulatory regions of a novel promoter sequence shown below, four 150 bb deletion constructs were made in a luciferase reporter system as indicated in the diagram in boxes A to D. After transfection, the observed level of promoter activity (%) as analyzed by luciferase assay of all the constructs is indicated in the right of the figure. Identify the best correct combination of regions in the options given below that indicate the presence of a positive and a negative regulatory element, respectively.

luciferase reporter system

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a. B and D
b. A and C
c. A and D
d. A and B

(89). Following sets of Plasmodium falciparum sporozoites

A. Normal sporozoites
B. Sporozoites with mutation in the C terminal of circumsporozoite (CS) antigen
C. Sporozoites with mutation in the N-terminal region of circumsporozoite (CS) antigen

Are injected into 2 groups of mice, one normal (group A) and one (group B) where localized knock down of heparin sulfate receptor for CS antigen in liver cells is achieved by injecting specific shRNA expressing lentiviral particles in the liver prior to infection. 15 days post infection, parasitemia is measured by counting infected RBC through Giemsa staining.

Which of the following groups will show maximum level of parasitemia?

a. Group B with set (i)
b. Group A with set (ii)
c. Group A with set (iii)
d. Group B with set (ii)

(90). Patients suffering from familial hypercholesterolemia (FH) are mostly homozygous for the defective gene and have profoundly elevated levels of serum cholesterol. The reason may be that the gene of highly specific receptor for LDL is either defective or missing in these patients. In an experiment, cells were taken from both normal individual and homozygote (FH) subjects, incubated in buffer with 125I labeled LDL in presence or absence of excess unlabeled LDL for various time periods and then 125I- labeled LDL bound to cells was measured. Which of the following is the best fit graph for the above experiment?

hypercholesterolemia

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(91). Collagen is the most prevalent extracellular matrix protein. Which of the following is NOT true for collagen?

a. Collagen is composed of triple helix consisting of two a polypeptide chain and one ß polypeptide chain wound around one another in a rope-like structure.
b. Glycine accounts for almost one third of the amino acids within collagen molecule.
c. Ascorbate is essential for collagen formation required for hydroxylation of proline.
d. Individual collagen polypeptide chains are synthesized on membrane bound ribosomes with N-terminal signal sequence for directing them to ER lumen

(92). The following statements have been proposed for a cancer cell.

A. Binding of p53 with MDM2, a ubiquitin E3 ligase, is precondition for cancer progression.
B. Phosphorylation of a tyrosine residue in the C-terminus of human c-Src is essential for cell invasion and motility.
C. Loss of function of both alleles of a tumor suppressor gene prevents metastasis.
D. Dimerization of c-myc-Max leads to enhanced cell proliferation

Which of the combinations of the above statements is correct?

a. A and B
b. C and D
c. A and D
d. B and C

(93). CD4+ T cells are co-cultured with macrophages in the presence of immobilized anti-CD3 antibody under four different conditions:

A. Interleukin (IL)-4 plus anti-IFNγ antibody
B. IL-12 and anti-IL-4 antibody
C. Transforming growth factor (TGF)-ß
D. TGF-ß and IL-6

For three rounds to induce T-helper cell differentiation identifiable by the cytokines they express predominantly. Which one of the following is the most likely combination of predominant cytokine expression in these cultures?

a. (A) IL-4, (B) INF-γ, (C) IL-10, (D) IL-17
b. (A) INF- γ, (B) IL-4, (C) IL-17, (D) IL-10
c. (A) IL-17, (B) IL-4, (C) INF- γ, (D) IL-10
d. (A) IL-17, (B) IL-10, (C) IL-4, (D) INF- γ

(94). Four groups of one-day old female BALB/c neonates had received the following treatments:

A. Epidermal cells from C57BL/6 male plus anti-ß-2 microglobulin antibody
B. Epidermal cells from C57BL/6 male plus antibodies to ß2 microglobulin, CD40 ligand, CD80 and CD86.
C. Epidermal cells from C57BL/6 female plus anti-CD80 antibody.
D. Epidermal cells from C57BL/6 female mice.

When these BALB/c neonates grew six weeks old, they received skin transplant from C57BL/c male mice. Transplantation rejection time varied between these four groups. Starting from the fastest to the slowest rejection, which one of the following is the most likely order?

a. D = C > A > B
b. A > B > C = D
c. B > A > D = C
d. D > B = C > A

(95). At the 2 celled stage of Caenorabditis elegans development the blastomeres were experimentally separated and allowed to proceed in development. One of the blastomere (P1) developed generating all types of cells it would normally make while the other blastomere (AB) made only a fraction of the cell types it would normally make. The following conclusion can be drawn:

A. The determination of both P1 and AB was autonomous
B. The determination of both P1 and AB was conditional
C. The determination of P1 was autonomous and AB was conditional
D. Both asymmetric division and cell-cell interactions specify cell fate in early development.

Which of the above combinations is correct?

a. A and C
b. B and D
c. A and D
d. C and D

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