#Question id: 23912
#General Aptitude
#Question id: 16110
#Unit 7. System Physiology – Animal
#Question id: 2067
#Unit 2. Cellular Organization
Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly?
#Question id: 19822
#Unit 12. Applied Biology
Recognition of which molecules by receptor-like molecules present in resistant plants initiates several biochemical reactions?
#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?