How do proteins function in plasma membranes?
Select the correct answer.
Answer
A separate the cell from the extracellular environment
B arrange in such a way that they provide barriers for organelles and the cell itself
C hydrophobic membrane-spanning regions interact with the hydrophobic tails of phospholipids
D play a role in viral immunity
The correct answer and explanation is:
The correct answer is C. Hydrophobic membrane-spanning regions interact with the hydrophobic tails of phospholipids.
Explanation:
Proteins in plasma membranes play a crucial role in maintaining the cell’s structure, communication, and function. The plasma membrane is primarily composed of a lipid bilayer, with proteins embedded throughout. These proteins can either span the membrane (integral proteins) or be attached to the surface (peripheral proteins).
The most important aspect of membrane-spanning proteins is their interaction with the lipid bilayer. The plasma membrane is made up of phospholipids, which have hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails. The hydrophobic tails are oriented toward the interior of the membrane, while the hydrophilic heads face outward, toward the watery extracellular environment and the cytoplasm.
Proteins that span the membrane have hydrophobic regions that interact with these hydrophobic tails of phospholipids. This interaction helps anchor the proteins within the membrane, allowing them to perform various functions, such as transport, signal transduction, and structural support. For example, many membrane proteins act as channels or carriers to facilitate the movement of molecules across the membrane, a critical function for maintaining cellular homeostasis.
Some proteins also have hydrophilic regions exposed on the outside or inside of the cell. These regions interact with the aqueous environment, allowing the proteins to participate in signaling or act as receptors for external signals, such as hormones or neurotransmitters.
The proper arrangement of these proteins in the membrane is essential for cell function, as they play roles in communication, immune response, and intracellular signaling. Thus, the hydrophobic interaction between membrane-spanning proteins and phospholipids is a key feature of how proteins function in plasma membranes.