Which type tends to have straighter tails due to packing tightly?

Which type tends to have straighter tails due to packing tightly?

• A. Cis unsaturated fatty acids
• B. Monounsaturated fatty acids
• C. Polyunsaturated fatty acids
• D. Trans unsaturated fatty acids

Answer: (D)

Double-bond geometry determines how a fatty acid tail sits in the lipid bilayer. A cis double bond creates a kink in the tail because the hydrogens are on the same side, bending the chain and preventing tight packing. Trans double bonds keep the tail nearly straight since the hydrogens are on opposite sides, so the chain remains linear enough to align with neighboring tails. This allows tighter packing, similar to saturated fats, and gives the tails a straighter appearance with a higher melting point. Monounsaturated and polyunsaturated fats have one or more cis double bonds, introducing bends that disrupt tight packing and keep membranes more fluid.

Double-bond geometry determines how a fatty acid tail sits in the lipid bilayer. A cis double bond creates a kink in the tail because the hydrogens are on the same side, bending the chain and preventing tight packing. Trans double bonds keep the tail nearly straight since the hydrogens are on opposite sides, so the chain remains linear enough to align with neighboring tails. This allows tighter packing, similar to saturated fats, and gives the tails a straighter appearance with a higher melting point. Monounsaturated and polyunsaturated fats have one or more cis double bonds, introducing bends that disrupt tight packing and keep membranes more fluid.