AP BIOLOGY

Detailed explanation-1: -These channels are glycoproteins (proteins with carbohydrates attached) that allow molecules to pass through the membrane. These channels are almost always specific for either a certain molecule or a certain type of molecule (i.e. an ion channel), and so they are tightly linked to certain physiologic functions.

Detailed explanation-2: -A transport protein completely spans the membrane, and allows certain molecules or ions to diffuse across the membrane. Channel proteins, gated channel proteins, and carrier proteins are three types of transport proteins that are involved in facilitated diffusion.

Detailed explanation-3: -In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers.

Detailed explanation-4: -Passive transport is the mechanism by which most drugs cross cell membranes. If two solutions are separated by a partially permeable membrane, a solute will pass from the side where it is more concentrated to the side where it is less concentrated.

Detailed explanation-5: -Facilitated diffusion uses integral membrane proteins to move polar or charged substances across the hydrophobic regions of the membrane. Channel proteins can aid in the facilitated diffusion of substances by forming a hydrophilic passage through the plasma membrane through which polar and charged substances can pass.