Question

How do polar molecules enter the cell?

Answer 1

Hint :Polar molecules are the molecules in which one end is slightly positive and the other end is slightly negative. In case of polar molecules, the electrons are distributed unevenly between the covalent bond.

Complete Step By Step Answer:
To solve this question, we must know about the movement of polar molecules.
The movement of molecules across the membrane is carried out by both active and passive transport systems. In active transport, the molecules move across the membrane against the concentration gradient that is from lower concentration to higher concentration. In passive transport, the molecules cross the membrane in accordance with the concentration gradient.
The cell membrane is lipo-proteinaceous in nature. It contains lipid bilayer and proteins. The lipid is the nonpolar part which helps in transport of the non-polar proteins.
The polar molecules cross the membrane by both active and passive transport. The polar molecule can only attach to polar proteins. The channel proteins present in the cell membrane are polar in nature and help in transporting the polar molecules across the cell membrane. These channel proteins change their shape in accordance with the molecules they have to transport. The channel proteins used the gated system which opens and closes in accordance with the polar molecules.

Note :
The polar molecules cannot cross the lipid bilayer as they are hydrophilic in nature. The transmembrane proteins help in transporting the polar molecules across the membrane. Thus, these proteins are known as transporters. Glucose is an example of a polar molecule which is transported across membranes by the help of transporters.