The straight lipophobic transmembrane segments have clustered around each other and the lipids have been excluded from the central portion of the structure. Ion Channels and Charge Proteins can change shape. This may be due to a variety of inputs. One result of this capacity, is that we can have, e.g., a channel that can open and close. We therefore have a mechanism for controlling the flow of ions or molecules into and out of the cell.
Gates can be very specific.
We have sodium gates, potassium gates, and calcium gates, to name a few. It is possible to have more negative ions in the cell than positive ions. The inside of the cell then becomes negative with respects to the outside of the cell. This establishes a potential across the cell membrane, which encourages the diffusion of positively charged ions into the cell and negatively charged ions out of the cell. There are many ways for transport to occur across the cell membrane.