Match the columns and choose the correct option.

Column I	Column II
A.    Progress zone	i.                    thickening of the ectoderm at the apex of the developing limb bud
B.     Apical ectodermal ridge	ii.                  The cells found within the most posterior region
C.     Zone of polarizing activity	iii.                The highly proliferative mesenchyme that fuels limb bud growth

#Question id: 1257

#Unit 4. Cell Communication and Cell Signaling

Following statements are regarding to protein kinase A which phosphorylates multiple intracellular target proteins expressed in different cell types.

A. Inactive PKA is a tetramer consisting of two regulatory (R) subunits and two catalytic (C) subunits.

B. Each R subunit contains a pseudo-substrate domain whose sequence resembles that of a peptide substrate and binds to the active site in the catalytic domain but is not phosphorylated; thus the pseudo-substrate domain inhibits the activity of the catalytic subunits.

C. active PKA is turned off by binding of cAMP Each R subunit has two distinct cAMP-binding sites, called CNB-A and CNB-B.

D. Binding of cAMP by an R subunit of PKA occurs in a cooperative fashion; that is, binding of the first cAMP molecule to CNB-B increases the Kd for binding of the second cAMP to CNB-A. Thus small changes in the level of cytosolic cAMP can cause proportionately large changes in the number of dissociated C subunits and, hence, in cellular kinase activity.

Which of the following statements are incorrect?

#Question id: 19290

#Unit 9. Diversity of Life Forms

#Question id: 2036

#Unit 4. Cell Communication and Cell Signaling

Certain microorganism such as Salmonella, Listeria, Neisseria, Cryptococcus consist of specific carbohydrate moieties on the surface antigen that activate

#Question id: 14523

#Unit 13. Methods in Biology

#Question id: 2873

#Unit 2. Cellular Organization

With reference to aberrant methylation of bases which of the following statements, if any, is false?