AP BIOLOGY

Detailed explanation-1: -By acting as a gatekeeper, the plasma membrane protects the cell from its surroundings and keeps important molecules from leaving the cell, so that the correct balance of molecules is maintained.

Detailed explanation-2: -Protein machineries embedded in the membranes of our cells act as ‘gatekeepers’ controlling everything transported in and out of every cell in our bodies. Because these machineries, called membrane embedded proteins, are vital to the way our bodies function they are the target of at least 40% of drugs.

Detailed explanation-3: -Membrane proteins, the gatekeepers of cells, have been implicated in neurotransmission, sensing, and transport of nutrients and drugs into and out of cells.

Detailed explanation-4: -A: Facilitated diffusion works like a gate, the cell membrane acts as the gate keeper. When something that wants to enter a cell reaches a cell membrane and it can not enter via diffusion, a gate will open and allow the molecule to enter. The proteins that sit on the outside of the cell membranes act as the gates.