Question

A molecule needs to enter into the cell but cannot go through the plasma membrane because of its polarity. However, the molecule can bind to a _______ protein and the protein changes shape to allow the particle to move through the membrane.

Answer 1

The molecule that cannot pass through the plasma membrane due to its polarity can bind to a carrier protein, which changes shape to transport the substance into the cell.

Step-by-step explanation:

The molecule that needs to enter the cell but cannot pass through the plasma membrane due to its polarity can bind to a carrier protein.

These proteins are embedded in the plasma membrane and play a crucial role in the transportation of molecules. Upon binding a substance, a carrier protein undergoes a change in shape, allowing the substance to move from outside the cell to the interior.

This process, known as facilitated diffusion, is important for polar substances and ions, which cannot readily diffuse through the hydrophobic core of the lipid bilayer of the cell membrane.

Each carrier is specific to a single substance and the number of these proteins in any membrane is finite.

This specificity and finite number of proteins help maintain the selective permeability of the plasma membrane.

However, once all of these proteins are bound to their ligands, they become saturated and can cause a bottleneck in transport if the demand for the molecule is high.