Final answer:
Charge impedes charged or hydrophilic substances from passing through the hydrophobic core of the cell membrane, necessitating special proteins to aid their transit. Membrane fluidity also influences permeability, with higher fluidity facilitating substance passage. Transport mechanisms like the sodium/potassium pump are essential for moving charged particles across the membrane.
Step-by-step explanation:
Charge plays a crucial role in lipid solubility and permeability across the cell membrane. The phospholipid bilayer of the cell membrane is hydrophobic inside, which makes it impermeable to charged or hydrophilic substances without assistance. Charged particles can't pass through this hydrophobic core on their own because they are repelled by the hydrophobic tails of the phospholipids. Consequently, charged molecules, such as ions, rely on special membrane proteins like channel proteins to help them cross the membrane.
Moreover, the membrane's fluidity can be affected by factors such as temperature, the degree of saturation of fatty acids, and the presence of cholesterol, which in turn influences its permeability. Higher fluidity generally allows for easier passage of substances, whereas lower fluidity, often achieved by the presence of cholesterol, makes the membrane less permeable. Specific transport mechanisms like the sodium/potassium pump actively regulate the concentration of ions inside and outside the cell, overcoming the challenges posed by the charged nature of these particles.