AP BIOLOGY

Detailed explanation-1: -Channel proteins span the membrane and make hydrophilic tunnels across it, allowing their target molecules to pass through by diffusion. Channels are very selective and will accept only one type of molecule (or a few closely related molecules) for transport.

Detailed explanation-2: -Carrier proteins and channel proteins are the two major classes of membrane transport proteins. Carrier proteins (also called carriers, permeases, or transporters) bind the specific solute to be transported and undergo a series of conformational changes to transfer the bound solute across the membrane (Figure 11-3).

Detailed explanation-3: -From the endoplasmic reticulum, proteins are transported in vesicles to the Golgi apparatus, where they are further processed and sorted for transport to lysosomes, the plasma membrane, or secretion from the cell.

Detailed explanation-4: -Membrane transport proteins fulfill an essential function in every living cell by catalyzing the translocation of solutes, including ions, nutrients, neurotransmitters, and numerous drugs, across biological membranes.