Final answer:
Membrane fluidity is the viscosity of the cell membrane, influenced by temperature and lipid composition. Higher temperatures and more unsaturated fats increase fluidity. Cholesterol stabilizes fluidity by preventing excessive changes during temperature fluctuations.
Step-by-step explanation:
Membrane Fluidity
Membrane fluidity refers to the viscosity of the lipid bilayer of a cell membrane, which affects how easily its components (phospholipids and proteins) can move within the layer. Increased fluidity allows for easier movement of substances across the membrane and better interaction of membrane proteins, essential for various cellular processes.
Factors Affecting Membrane Fluidity
Factors that increase membrane fluidity include higher temperatures and the presence of more unsaturated fatty acids with double bonds (C=C) in the phospholipids' hydrophobic tails, which create kinks and space for more movement. Conversely, factors that decrease fluidity include lower temperatures and the presence of cholesterol, which fills in gaps between phospholipid tails and reduces mobility.
Cholesterol's Role in Membrane Fluidity
Cholesterol functions as a buffer in animal cell membranes, mitigating the effect of temperature changes. At normal temperatures, it ensures optimal fluidity. When temperatures are high, cholesterol prevents excessive fluidity, and during low temperatures, it prevents the membrane from becoming too rigid, thus maintaining a consistent level of fluidity for cellular functions.