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

Secondary messenger molecules are usually small molecules like cAMP and Ca2+ ions. These molecules relay the signalling function induced by primary messenger molecule like hormone. These molecules are required for two reasons, one is because the primary messenger molecule cannot pass through the plasma membrane due to their bulky size. Also these molecules amplify the signal induces by hormones to manyfolds. For primary messenger like hormone to amplify the signal to this extent, a large amount of hormone molecule will be needed which is a bulky molecule itself and have problems entering the cell membrane firstly.

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