The property of biological membranes that describes the ability of individual molecules to move within the membrane is called membrane fluidity. Membrane fluidity refers to how freely phospholipids and proteins can move laterally within the lipid bilayer of the membrane. This fluid character allows the membrane to be flexible and dynamic rather than rigid, enabling molecules to diffuse and interact within the membrane plane

. Factors influencing membrane fluidity include:

• The types of fatty acids in the phospholipids: Unsaturated fatty acids with double bonds create "kinks" that prevent tight packing and increase fluidity, while saturated fatty acids make the membrane more rigid

• Temperature: Higher temperatures increase fluidity by providing lipids with more thermal energy to move

• Cholesterol: Acts as a fluidity buffer, preventing membranes from becoming too fluid at high temperatures or too rigid at low temperatures

In summary, membrane fluidity is the key property describing the ability of molecules to move within the biological membrane. It is essential for membrane function, allowing proteins and lipids to diffuse, interact, and maintain membrane integrity