What is necessary for a target cell to respond to a cell signaling molecule?
A)being close together
B)a second messenger
C)specific receptor proteins
D)All apply.

Question

Quizplus · Accepted Answer

Specific receptor proteins are necessary for a target cell to respond to a cell signaling molecule. Receptor proteins bind to the signaling molecule and initiate a response within the cell.

Answer: D
 Being close together is not necessarily needed for a target cell to respond to a cell signaling molecule. However, a second messenger may be involved in some signaling pathways to amplify the signal and initiate a response within the cell. Therefore, all the given options apply to varying degrees.

What Is Necessary for a Target Cell to Respond to a Cell