Final answer:
Facilitated diffusion is the process by which molecules passively transport across the cell membrane through specific proteins without using cellular energy. It is crucial for the movement of substances that are too large, polar, or charged to diffuse through the lipid bilayer of the membrane directly.
Step-by-step explanation:
The process often utilized by protein molecules embedded in a structure for movement across the cell membrane without using energy is known as facilitated diffusion. This process involves the passive transport of molecules, such as glucose, amino acids, and ions, across the cell membrane through specific proteins like channel or carrier proteins. Unlike active transport, which requires energy in the form of ATP to move substances against their concentration gradient, facilitated diffusion harnesses the concentration gradient to move substances from an area of higher concentration to an area of lower concentration, without the expenditure of cellular energy.
Carrier proteins play a crucial role in this process by binding to the specific molecule and changing shape to transport it across the membrane. Similarly, channel proteins provide a passageway for molecules to diffuse through the membrane. The process is vital for transporting substances that cannot move across the lipid bilayer due to their size, polarity, or charge, and it ensures that cells can maintain homeostasis by regulating the internal composition of solutes.