At any given time there is an array of signaling molecules i

At any given time, there is an array of signaling molecules in a cell\\\'s environment. How does a cell \\\"know\\\" which signaling molecules to respond to?

A)A cell responds to a signaling molecule only if the cell has the appropriate receptor.

B)A cell responds only to signaling molecules that can enter the nucleus.

C)A cell responds only to signaling molecules from neighboring cells.

D)A cell responds only to paracrine signaling molecules.

E)A cell responds only to signaling molecules that are targeted to that specific cell.

Solution

The correct answer is (A).

The type of signal a cell receives only depends on the presence of a receptor to which the ligand can bind to. If both the receptor and the ligand are present, the signalling cascade will take place, regardless of whether the signalling is target or non-target. Even for the signalling molecules that can enter the nucleus, the cascade will occur only when the receptor is present. The signalling molecules could be paracrine, endocrine, from neighbouring or from far off cells.