2.

Which of the following is the best description of the fluid mosaic model?

A fluid triglyceride bilayer with embedded proteins.

A fluid phospholipid bilayer with embedded proteins.

A stationary triglyceride bilayer with fluid proteins.

A stationary phospholipid bilayer with proteins that change positions.

2.

Which of the following is the best description of the fluid mosaic model?

A fluid triglyceride bilayer with embedded proteins.

A fluid phospholipid bilayer with embedded proteins.

A stationary triglyceride bilayer with fluid proteins.

A stationary phospholipid bilayer with proteins that change positions.

Answer: A fluid phospholipid bilayer with embedded proteins.

Explanation: Biological membranes are composed of phospholipids and proteins. Phospholipids lipids have two parts: The polar / hydrophilic head groups and the nonpolar/hydrophobic tails. The polar head groups is composed of the phosphate group while the nonpolar tail is composed of the fatty acyl chains. The fatty acyl chains of the phospholipids interact by facing each other, forming a bilayer with a hydrophobic interior while the polar head groups face outward where they interact with water. Proteins are embedded in this sea of lipids where they float laterally. The proteins are held in the bilayer by noncovalent interactions between the hydrophobic regions of the proteins and the hydrophobic tails of the phospholipids. The fluid mosaic model of the membrane is because most of the interactions between the components of the membrane are noncovalent, thereby leaving the proteins and lipids free to move laterally in the plane of the bilayer but movement from one face of the bilayer to another is restricted.