Which factor does NOT influence membrane fluidity?

Membrane fluidity is primarily influenced by several key factors, including cholesterol presence, temperature, and the types of fatty acids that make up the phospholipid bilayer.

Cholesterol molecules are interspersed within the phospholipid bilayer and serve to stabilize the membrane. At higher temperatures, cholesterol can help prevent the membrane from becoming too fluid, while at lower temperatures, it prevents the membranes from becoming too rigid. This modulation of fluidity supports the proper function of membrane proteins and the overall integrity of the cell.

Temperature plays a crucial role because it affects the kinetic energy of the lipid molecules. As temperature increases, the fluidity of the membrane also increases, allowing for better movement of proteins and lipids. Conversely, lower temperatures decrease fluidity as lipids become more closely packed.

The types of fatty acids present in the membrane, specifically whether they are saturated or unsaturated, also significantly affect fluidity. Unsaturated fatty acids have one or more double bonds that create kinks in the hydrocarbon chains, preventing them from packing closely together and thus increasing fluidity. In contrast, saturated fatty acids allow closer packing, resulting in a more rigid membrane structure.

The concentration of proteins within the membrane, however, does not directly influence fluid