Water and electrolytes like Na⁺ and Cl^- are lost from the body in diarrhea. Oral administration of NaCl solution in this condition does not improve the situation. When glucose is administered with normal NaCl solution through the oral route, the absorption of electrolysis along with water occurs and the patient recovers.

A. Glucose enhances ATP production in the mucosal cells of the small intestine and thus facilitates sodium absorption.

B. Glucose inhibits the diarrheal toxin induces cAMP production in the mucosal cells of the small intestine.

C. Na⁺ is co-transported with glucose on the apical surface of the mucosal cells of the small intestine.

D. The epithelial sodium channels (ENaC) are activated by glucose in the colon.

Which one of the following is true?

• Only A

• A and B

• Only C

• C and D

An EEG was recorded and its power spectrum analyses were done in rats with implanted electrode for a long time. The power of the EEG waves decreased two months after electrode implanation.

This observation may be due to the following:

A. Glial cells accumulate surrounding the exposed tips of electrodes.

B. Degeneration of neurons occur surrounding the electrode tips due to metal ion deposition.

C. Coating of electrodes are destroyed with time. 

D. The microsocket becomes loose with time.

Which one of the following is true?

• Only A

• A and B

• Only C

• C and D

Membrane-bound and free ribosomes, are structurally identical, but differ only at a given time in terms of association with

• acetylated proteins

• glycosylated proteins

• phospholipids

• nascent proteins

The dye used in Gram staining is

• Rhodamine

• Methylene blue

• Giemsa

• Crystal violet

Each origin of replication is activated only once. This is achieved because

• pre-replicative complex can only form in G1 and replication can only be initiated when the pre-replication complex is disassembled at the beginning of S-phase.

• replication can only be initiated when pre-replication complex is intact.

• replication can only be initiated when unphosphorylated Rb is present.

• pre-replicative complex can only form S-phase.

Histone acetylase and chromatin remodeling complexes are recruited to specific regions of chromatin by

• gene activator proteins.

• specific promoter sequence

• phosphorylation of histone acetylase

• dephosphorylation of chromatin remodeling complexes

The distance between bacterial genes as determined from interrupted mating mating experiments are measured in units of

• cM

• minutes

• bp

• micrometers

68.

The tetrapeptide "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 tetrapeptide is not allowed in terms of its binding with its receptor and its subsequent retention in specific organelle whereas, secretory proteins are devoid of such tetrapeptide. From this observation indicate the localization of the receptor of this tetrapeptide:

• Plasma membrane

• Golgi

• Endoplasmic reticulum

• Mitochondria

¹²⁵I-labelled diaminofluorene (DAF) is a well known photoactivable hydrophobic probe of plasma membrane integral protein. To determine the approximate length and number of hydrophobic domains 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:

• The intact membrane was allowed to interact with DAF and unincorporated DAF measured.

• 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.

• Intact membrane was allowed to interact with DAF, then membrane was solubilized with detergents, digested with proteases (limited proteolysis) run on SDS-PAGE followed by autoradiography.

• Intact membrane was allowed to interact with DAF followed by complete proteolysis, SDS-PAGE, and finally autoradiography.

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?

• Region 2 pairs with region 3 allowing transcription of the structural genes.

• Region 1 and 2 will pair, allowing 3 and 4 to pair leading to attenuation.

• There is no pairing in the trpL region and transcription of structural gene occurs.

• Region 2 and 3 will pair leading to attenuation.