Calcium ions could be described as \"third messengers\" because __________. a. t
ID: 256780 • Letter: C
Question
Calcium ions could be described as "third messengers" because __________.
a. they function in three separate cellular compartments: cytosol, ER, and mitochondria
b. they are stored in compartments inside the cytoplasm, placing them in a third compartment after the extracellular and cytosolic spaces
c. they are small cytosolic signal molecules whose activity is regulated first by a ligand and second by a second messenger, making them the third step in a cascade
d. they are the third type of regulators released by a G protein-mediated signal cascade (cAMP = 1st IP3/DAG 2nd)
Explanation / Answer
The correct answer is option C - They are small cytosolic signal molecules whose activity is regulated first by a ligand and second by a second messenger, making them the third step in a cascade.