Membrane Fluidity

What does it mean when we say cell membranes are fluid

It means the membrane’s lipids and proteins are not fixed in place, they can move and change shape, giving the membrane flexibility.

What mainly affects membrane fluidity

The types of fatty acids in the phospholipid bilayer (saturated vs. unsaturated)

What is special about unsaturated fatty acids

They have double bonds that create kinks in their hydrocarbon tails

How do unsaturated fatty acids affect membrane fluidity

The kinks prevent tight packing of lipids, making the membrane less viscous and more fluid

How do unsaturated fatty acids affect melting point

They have lower melting points, keeping membranes flexible at lower temperatures

What is special about saturated fatty acids

They have no double bonds, so their tails are straight

How do saturated fatty acids affect membrane fluidity

They pack tightly together, making the membrane more viscous and less fluid

How do saturated fatty acids affect melting point

They have higher melting points, so membranes stay strong and stable at high temperatures

What is homeoviscous adaptation

The process by which organisms adjust their membrane lipid composition to maintain proper fluidity under different temperatures

How do cells adjust fatty acid composition with temperature

1. At low temperatures → more unsaturated fatty acids (to stay flexible).

2. At high temperatures → more saturated fatty acids (to stay stable).

Why is regulating membrane fluidity important for poikilothermic organism

Because their body temperature changes with the environment, so they must adjust their membranes to keep them functional (e.g., Antarctic fish)

What is this digrame showing

Unsaturated Fatty Acids

What is this digrame showing

Saturated Fatty Acids