Total RNA was isolated separately from the cytosol and nuclei of human cells growing in a cell culture. Each sample was mixed with a purified denatured fragment of DNA corresponding to a large intron of a housekeeping gene and incubated under renaturating condition. Given below are the statements made about the outcome of the experiment.

A. RNA isolated from nuclei will form RNA-DNA duplexes because of the presence of introns in the primary RNA.

B. Cytosolic RNAs usually will not form RNA-DNA duplexes.

C. Both cytosolic and nuclear RNA will not form RNA-DNA duplexes as transcription and splicing occur simultaneously.

D. Cytosolic RNA will form RNA-DNA duplexes because unspliced cytosolic RNAs are exceptionally stable.

Which of the above statement(s) is/ are most likely to be true?

• Only C

• A and D

• A and B

• Only D

242.

The expression of a hypothetical gene was analyzed by Northern and Western blot hybridizations under control and induced condition. The results are summarized below:

Expression of genes can be regulated by:

A. control at transcription initiation

B. alternative splicing

C. control of translation initiation

D. protein stability

Which of the above regulatory mechanisms can explain the observations shown in the figures?

• Only B

• Only A and B

• Only B and C

• A, B, C and D

The following graph represents the expression of tryptophan synthetase (TS) in E.coli cells in the absence ($▢$) or presence ($■$) of tryptophan in the medium.

If the two trp codons in the leader sequence of top operon is mutated to ala, which of the following graphs will best represent activity of TS in E.coli cells grown in the absence or presence of tryptophan?

A newly identified sequence was experimentally tested by in vitro transport assay using a radiolabeled protein-containing the sequence to test import into mitochondria. Transport assay was done for a short time with or without membrane potential and after the assay, the mitochondria were either treated or not treated with proteinase K. At the end of the assay, the mitochondria were pelleted and the total protein of the pellet was isolated and separated on SDS-PAGE and autoradiography. A representative autoradiogram is shown below. Based on this experimental data, which of the following statements is NOT correct.

• The protein goes into the matrix.

• Not all of the added protein was imported

• The protein requires membrane potential for import.

• The protein is associated with the outer mitochondrial membrane.

If a researcher intends to identify a specific brain area activity linked to a cognitive function in human subjects, which one of the following techniques should be used?

• CAT

• MRI

• fMRI

• Patch-clamp

Which of the following statements is INCORRECT for fluorescence in situ hybridization (FISH) technique?

• A fluorescence or confocal microscope is used for the detection of signal.

• A labeled sequence of nucleotides is used.

• Specific fluorescence tagged antibodies are used.

• A stringent washing step is essential to remove the appearance of non-specific signals.

Lower limits of detection by sensors is important. Which method of detection is more sensitive than glass electrode used for pH measurement?

• Absorption spectroscopy

• Refractive index

• Circular dichroism

• Fluorescence spectroscopy

You want to purify a recombinant protein of your interest. You can use affinity chromatography to purify as you have nickel columns available in the laboratory. With what molecule will you tag the protein to purify those columns?

• GST

• Histidine

• Histamine

• Proline

If you run a pentavalent IgM through SDS-polyacrylamide gel electrophoresis, how man bands you are supposed to get by Western blotting using alkaline phosphatase-conjugated secondary antibody?

• Five

• Four

• Three

• One

The following graphs depict variation in the value of Dollar and Euro in terms of the Rupee over six months.

Which of the following statements is true?

• Values of Dollar and Euro rose steadily from January to June.

• Values of Dollar and Euro rose by equal rate between January to March.

• The rise in the value of Dollar from April to May is three times the fall in Euro during the same period.

• Values of Dollar and Euro rose equally between May and June.