Question

a second messenger participates in a signal transduction pathway by ... question options: a) transporting a signal molecule through the hydrophobic centre of the plasma membrane. b) relaying a message by phosphorylating downstream proteins. c) dampening the message once the signal molecule has left the receptor. d) amplifying a message from the cytosolic side of the membrane throughout the cytosol. e) relaying a signal from the outside to the inside of the cell.

Answer 1

Second messengers amplify cellular messages by transmitting signals within the cell, activating kinases such as cAMP⁻ dependent kinase, leading to a cascade of protein phosphorylations, ultimately eliciting a cellular response.

Step-by-step explanation:

A second messenger participates in a signal transduction pathway primarily by d) amplifying a message from the cytosolic side of the membrane throughout the cytosol. Second messengers are small, non-protein molecules that propagate a signal within the cell after it has been initiated by the binding of a signaling molecule to a receptor.

These messengers help spread a signal through altering the behavior of cellular proteins. For example, cyclic AMP (cAMP) is synthesized from ATP and plays a critical role in activating cAMP⁻ dependent kinase (A-kinase), which then phosphorylates target proteins to produce a cellular response.

Another common second messenger is Ca²⁺, which also plays a significant role in cell signaling.