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.

#Question id: 5126

#SCPH01 Biochemistry

Which one is correct according to adult stem cell lineage?

#Question id: 5127

#SCPH01 Biochemistry

The following are certain statements regarding stem cells. Which one is correct?

#Question id: 5128

#SCPH01 Biochemistry

During lens formation in the Xenopus, the following statements have been proposed. Which statement is incorrect?

#Question id: 5129

#SCPH01 Biochemistry

once the lens has formed, it induces other tissues. One of these responding tissues is the optic vesicle itself; thus, the inducer becomes the induced. Under the influence of factors secreted by the lens, the optic vesicle becomes the optic cup, and the wall of the optic cup differentiates into two layers: the pigmented retina and the neural retina. such interactions are called as-

#Question id: 5130

#SCPH01 Biochemistry

Regulation by gradients of paracrine factor concentration was elegantly demonstrated by the specification of different mesodermal cell types in the frog Xenopus laevis by activin, a paracrine factor of the TGF-beta family. Which of the following observations are correct from this graph?

#Question id: 5131

#SCPH01 Biochemistry

Differentiated cells express the genes and proteins characteristic of their final identity in the adult, and that identity can be altered only under special circumstances. How does the concept of differentiation, as described here, differ from the concept of determination?