Second messenger is/are:
Ca2+
DNA
Histone
cDNA
Ans: a. Ca2+ [Ref Harper 30th/501, 91-92, 179, 343; Lippincott 6th/94-951Nucleotides, such as cyclic adenosine mono-phosphate (cAMP) and cyclic guanosine monophosphate (cGMP), serve as second messengers in signal transduction pathways.Two of the most widely recognized second messenger systems are the calciumlphosphatidy linositol system, and the adenylyl cyclase system, which is paicularly impoant in regulating the pathways of intermediary metabolism.