Question

List the main types of subtances that move through cell membranes. Which are polar or nonpolar? (Hydrophilic or Hydrophobic)

Answer 1

The main substances that moves across the cell membrane are listed below:-

1) O₂, CO₂, N₂, Steroids: These are non-polar, hydrophobic molecules, which can easily cross the cell membrane and hence there is no requirement of transport protein.

2) Water, Glycerol, Urea, Glucose: These are small and large uncharged polar, hydrophilic molecules and necessarily require transport proteins to cross the cell membrane.

3) Ions (Na⁺, K⁺, H⁺, Ca⁺², Cl^-): These are hydrophilic molecules which move across the cell membrane through voltage gated channels.