Question

The majority of signaling pathways include intracellular relay molecules (secondary messengers and proteins involved in cascades).

Clearly explain one reason why these intracellular signaling molecules are necessary and advantageous.

Answer 1

In various signalling pathways, the hormone or other primary messenger molecule binds to its extracellular receptor. Such binding generates a intracellular response in form of activation of a secondary messenger which further carries the signalling function.

Such secondary messenger molecules are important because most of the primary messenger molecules like various hormone are peptides and cannot cross plasma membrane readily. Even if they enter the cytoplasm they cannot activate the signalling function like activating transcritpion factors due to their large size as compared to secondary messenger molecules like cAMP (Cyclic adenosine monophosphate). This is one of the major reason why secondary messenger molecules are required for various signal transduction pathways.

Please give a thumbs up if the answer helped you. Thank you :)