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TLS Online TPP Program

#Question id: 892

Assisted protein folding is mediated by a group of proteins known as chaperons, which of the following statements is incorrectly reperesents chaperon activity;

#Unit 1. Molecules and their Interaction Relevant to Biology

  1. chaperon help to fold, unfolded and partially folded polypeptide chains to disrupt the improper association of exposed hydrophobic segments

  2. All molecular chaperones operate by binding to an unfolded or aggregated protein’s, and molecular chaperon donot requires ATP for their activity

  3. molecular chaperones function to lift folding polypeptides out of the false minima in their folding funnels

  4. molecular chaperones were first described as heat shock proteins (Hsp) because their rate of synthesis is increased at elevated temperatures

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TLS Online TPP Program

#Question id: 647

#Unit 1. Molecules and their Interaction Relevant to Biology

For the hypothetical reversible reaction where S is converted to P, the rate constant for the forward reaction is 105 s-1 while that of the backward reaction is 101 s-1. If the reaction is catalyzed by an enzyme, the rate constant for the forward reaction increases 100-fold. What will be the equilibrium constant of the enzyme catalyzed reaction?
TLS Online TPP Program

#Question id: 646

#Unit 1. Molecules and their Interaction Relevant to Biology

Many biosynthetic pathways are regulated by feedback inhibition of enzymes. In a particular type of feedback inhibition, two endproducts individually do not inhibit an enzyme upstream in the pathway at all, but when both are present they inhibit the same enzyme significantly. What type of feedback inhibition do these inhibitors represent?
TLS Online TPP Program

#Question id: 645

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is the correct combination of marker enzymes used to identify different organelles during subcellular fractionation of eukaryotic tissue?
TLS Online TPP Program

#Question id: 644

#Unit 1. Molecules and their Interaction Relevant to Biology

Enzyme X and Enzyme Y are both involved in monosaccharide metabolism. Enzyme X uses glucose as a substrate while Enzyme Y uses fructose as a substrate. At pH=7.0, Enzyme X has a Vmax of 10 μM/s while Enzyme Y has a Vmax of 20 μM/s. Both enzymes have a Km of 3.0 mM for their respective substrates. Which aspects of its reaction will be changed by Enzyme Y?
TLS Online TPP Program

#Question id: 643

#Unit 1. Molecules and their Interaction Relevant to Biology

The hydrolysis of lactose is catalysed by b-galactosidase as given below

Which of the following could be correct mechanism for this hydrolysis reaction?

A. Nucleophilic attack by the carboxylate group of Glu/Asp on the C-1 carbon atom of the galactose moiety within glucose, releasing glucose and forming an intermediate with the galactose linked to the enzyme through an ester linkage. Water then attacks this carbon atom, displacing the glutamate carboxylate and releasing galactose.

B. Electrophilic attack by the carboxylate group of Glu/Asp on the C-1 carbon atom of the galactose moiety within glucose, releasing glucose and forming an intermediate with the galactose linked to the enzyme through an ester linkage. Water then attacks this carbon atom, displacing the glutamate carboxylate and releasing galactose.

C. Nucleophilic attack by the carboxylate group of Lys/Arg/His or bivalent cation on the C-1 carbon atom of the galactose moiety within glucose, releasing glucose and forming an intermediate with the galactose linked to the enzyme through an ester linkage. Water then attacks this carbon atom, displacing the glutamate carboxylate and releasing galactose.
TLS Online TPP Program

#Question id: 642

#Unit 1. Molecules and their Interaction Relevant to Biology

The graphs P, Q and R show the variation of rate constant (k) with temperature. The reactions represented by P, Q and R, respectively, are