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.
Proteins in plasma membranes have several critical roles, but one of the most essential functions is their interaction with the lipid bilayer. The plasma membrane itself consists of a phospholipid bilayer, with hydrophilic (water-loving) heads facing the extracellular and intracellular environments, while hydrophobic (water-repellent) tails face inward, away from water. Membrane proteins, especially those that span the membrane, interact with this structure.
Many membrane proteins have hydrophobic regions that anchor them within the lipid bilayer. These hydrophobic regions interact with the hydrophobic tails of the phospholipids, helping to stabilize the protein within the membrane. Some membrane proteins span the entire membrane, creating channels or transporters that allow molecules to pass in and out of the cell. Others are involved in cell signaling or maintaining the cell’s shape.
Proteins that are embedded in or attached to the plasma membrane can serve various functions, such as acting as receptors for signals from the environment, providing structural support, or facilitating communication between cells. While proteins help separate the cell from its environment and perform functions in immunity, their key role is in maintaining the integrity and functionality of the membrane, particularly through their interaction with the phospholipid bilayer.
In conclusion, the correct option, C, describes the critical interaction between the hydrophobic parts of membrane proteins and the lipid bilayer. This interaction is essential for the protein’s positioning and functioning within the membrane.