Which of the following factors tend to increase membrane fluidity?

• A. Saturated fatty acids
• B. Longer fatty acid chains
• C. Increased temperature
• D. Higher cholesterol content

Answer: (C)

Verified step by step guidance

1. Understand that membrane fluidity refers to the viscosity of the lipid bilayer of a cell membrane, which affects its permeability and the movement of proteins within the membrane.
2. Recognize that temperature is a key factor affecting membrane fluidity. As temperature increases, the kinetic energy of the lipid molecules also increases, leading to greater movement and thus increased fluidity.
3. Consider the role of fatty acid saturation: Saturated fatty acids have no double bonds, allowing them to pack tightly together, which decreases fluidity. In contrast, unsaturated fatty acids have one or more double bonds, creating kinks that prevent tight packing and increase fluidity.
4. Evaluate the effect of fatty acid chain length: Longer fatty acid chains have more van der Waals interactions, which can decrease fluidity. Shorter chains have fewer interactions, leading to increased fluidity.
5. Analyze the role of cholesterol: Cholesterol can both increase and decrease membrane fluidity depending on temperature. At high temperatures, it stabilizes the membrane and decreases fluidity, while at low temperatures, it prevents tight packing of phospholipids and increases fluidity.