Question

What types of amino acid r groups do you think will line the channel protein interior?

a. Polar
b. Nonpolar

Answer 1

The interior of channel proteins is usually lined with polar and charged amino acids, which interact with the aqueous environment inside the channel. Non-polar amino acids are typically found on the exterior of membrane proteins, interacting with the hydrophobic core of the lipid bilayer.

Step-by-step explanation:

The channel protein interior is generally lined by polar and charged amino acids. This is because the interior of channel proteins is typically aqueous, meaning they will be in contact with water molecules passing through the channel. Polar or charged amino acids are hydrophilic, meaning they can interact favourably with water, which is crucial for the function of the channel in a cellular membrane.

On the other hand, the exterior of membrane-embedded proteins, which are in contact with the fatty acid tails of the phospholipid bilayer, will primarily consist of non-polar amino acids. These non-polar amino acids are hydrophobic and interact well with the hydrophobic core of the membrane, thus helping to anchor the protein within the membrane.

These differences in amino acid composition are essential for the proper folding and function of proteins in different cellular environments. For example, soluble proteins that are not associated with membranes typically have nonpolar amino acids on the interior and polar amino acids on the surface, the opposite of what is observed in membrane proteins.

Answer 2

In channel proteins, which facilitate the transport of substances across the cell membrane, the interior is typically lined with polar and charged amino acids to interact favorably with these substances. Non-polar amino acids tend to be located in the lipid bilayer or membrane-bound regions of proteins.

Step-by-step explanation:

The types of amino acid R groups lining the interior of a channel protein are predominantly polar and charged. This is due to the fact that channel proteins are involved in the transport of substances across the cell membrane where the substances are usually in aqueous (water-based) environments. Also, since channel proteins often transport ions, which are charged particles, the lining of the channel needs to be able to interact favorably with these polar or charged species. Therefore, the inner surface of channel proteins is lined with amino acids that have side chains capable of forming hydrogen bonds or electrostatic interactions with the substances they transport.

On the contrary, in the lipid bilayer itself or in membrane-bound regions of proteins, non-polar amino acids are more commonly found. These non-polar amino acids interact favorably with the hydrophobic tails of the phospholipids, anchoring the protein into the membrane.