What happens to the membrane protein (gray) when it is activated by the signal molecules?

The receptor protein that is embedded in the cellular membrane must accept the signal.

Explanation:

When it receives the signal this protein will then go through a conformational change. This will change the shape and how it interacts with the molecules around it. Different receptor protein will act in different ways.

As their name implies, GPCRs interact with G proteins in the plasma membrane. When an external signaling molecule binds to a GPCR, it causes a conformational change in the GPCR. This change then triggers the interaction between the GPCR and a nearby G protein.

What happens to the membrane protein (gray) when it is activated by the signal molecules?

The membrane protein interacts with the nearby GPCR.

this transfer is call conjunction

as in mitosis, dna replication occurs during interphase.   in meiosis, it occurs specifically in s phase of interphase 1.