81.

Cystic fibrosis transmembrane conductance regulator (CFTR) is known to control the transport of which ion?

• Ca²⁺

• Mg⁺²

• HCO₃^-

• Cl^-

Given below are some statements about prokaryotic and eukaryotic mobile genetic elements or transposons.

A. Most mobile genetic elements in bacteria transpose via an RNA intermediate.

B. Most mobile genetic elements in bacteria are DNA.

C. Mobile genetic elements in eukaryotes are only retrotransposons.

D. Both, RNA and DNA transposons are found in eukaryotes.

Choose the correct combination.

• A and C

• B and C

• A and D

• B and D

Collagens are the most abundant component of the extracellular matrix. In order to maintain normal physiological processes like wound healing, bone development, etc, which one of the following type of enzymes is most important?

• Peptidases

• Proteases

• Amylase

• Lipases

The mammalian oocyte prior to sperm entry is arrested at what stage of cell division?

• Prophase of mitosis

• Prophase of meiosis I

• G₁ phase of mitotic cell cycle

• Metaphase of meiosis II

'Segregation of alleles can occur at Anaphase I or at Anaphase II of meiosis'. With reference to this statement, which one of the following organism is an ideal model system for identifying the stage of allelic segregation at meiosis?

• Neurospora crassa

• Saccharomyces cerevisiae

• Drosophila melanogaster

• Pisum sativum

Glycolipids and sphingomyelin are produced by the addition of sugars or phosphorylcholine to ceramide on cytosolic and luminal surfaces, respectively, of the Golgi apparatus. Finally, after such modifications, these molecules are located on the outer half of the plasma membrane. What key events are responsible for such localization?

• Membrane fusion only.

• Action of Flippase and membrane fusion.

• Action of only Flippase

• Flip flop of these molecules in the Golgi membrane catalyzed by proton pump.

In an attempt to study the transport of secretory vesicles insulin along microtubules in cultured pancreatic cells, how would treatment with "colcemid" affect the transport of these vesicles?

• Colcemid induces polymerization of microtubules, which in turn would activate vesicular transport.

• Polymerization of microtubules is inhibited by colcemid, which in turn would inhibit the transport of secretory vesicles.

• Colcemid inhibits the vesicular trafficking through the inactivation of v-SNARE protein.

• Colcemid activates t-SNARE proteins and in turn activates vesicular transport.

When circular plasmids having a centromere sequence are transformed into yeast cells, they replicate and segregate in each cell division. However, if a linear chromosome is generated by cutting the plasmid at a single site with a restriction endonucleases, the plasmids are quickly lost from the yeast. It is known that genes on the plasmids are lost because of the instability of the chromosome ends. What could be done so as to restore its stability and can be inherited?

• Methylation of adenine residues of the plasmid.

• Complexing the plasmid ends with histone proteins.

• By incorporating telomere sequences to the end of plasmid.

• By incorporating acetylated histone proteins to the plasmid ends.

Rec 8 is a meiosis specific cohesin that maintains centromeric cohesion between sister chromatids in meiosis I. Which of the phenotypes listed below would you predict will be manifested in a rec8$∆$ yeast?

• Only low viability of dyads.

• Improper reduction division and low viability of tetrads.

• Improper equational division and low viability of dyads.

• Low tetrad viability with no effect on reduction division.

In context to lac operon, if two bacterial strains P₁ and P₂ with the genotypes O^CI⁺Z^- and O⁺I^-Z⁺ respectively, were used to produce mero-diploid daughter strain D, which one of the following statements correctly predicts the expression of Z gene (β-galactosidase activity) in all the three strains? (O⁺, I⁺, and Z⁺ denote the wild type allele of the respective genes).

• P₁ - No expression; P₂ - constitutive expression; D - Inducible expression

• P₁ - No expression; P₂ - constitutive expression; D - constitutive expression

• P₁ - No expression; P₂ - inducible expression; D - Inducible expression

• P₁ - Inducible expression; P₂ - constitutive expression; D - Inducible expression