Question

7 mark for review identify three macromolecules that are components of the plasma membrane in a eukaryotic cell and discuss the structure and function of each. note on your ap exam, you will handwrite your responses to free - response questions in a test booklet

Explanation:

1. Phospholipids: Structure - Have a hydrophilic (water - loving) head and two hydrophobic (water - fearing) tails. They form a bilayer in the plasma membrane. Function - Create a semi - permeable barrier that controls the movement of substances in and out of the cell.
2. Proteins: Structure - Can be integral (embedded in the membrane) or peripheral (associated with the surface). They have various shapes and sizes. Function - Act as transporters (facilitating the movement of molecules across the membrane), receptors (for cell - signaling), and enzymes (catalyzing reactions at the membrane).
3. Cholesterol: Structure - A steroid molecule. It is interspersed among the phospholipids in the membrane. Function - Maintains membrane fluidity; at high temperatures, it restricts movement of phospholipids to prevent excessive fluidity, and at low temperatures, it prevents the membrane from becoming too rigid.

Answer:

1. Phospholipids: Structure - Hydrophilic head and hydrophobic tails forming a bilayer. Function - Semi - permeable barrier.
2. Proteins: Structure - Integral or peripheral with diverse shapes. Function - Transporters, receptors, enzymes.
3. Cholesterol: Structure - Steroid molecule. Function - Maintains membrane fluidity.