Humber Admissions Practice Test

Which biomolecule is primarily involved in the structure and function of the cell membrane?

1. Carbohydrates

2. Proteins

3. Phospholipids

4. Nucleic acids

The correct answer is: Phospholipids

Phospholipids are the primary biomolecule involved in the structure and function of the cell membrane. They are crucial for forming the lipid bilayer, which serves as a fundamental framework of the membrane. Each phospholipid molecule has a hydrophilic (water-attracting) "head" and two hydrophobic (water-repelling) "tails." This unique structure allows phospholipids to arrange themselves in a bilayer, with the hydrophilic heads facing the aqueous environment both inside and outside the cell, while the hydrophobic tails face inward, away from water. This arrangement is essential for maintaining the integrity of the cell membrane, providing a barrier that separates the interior of the cell from its external environment. Additionally, the fluid nature of the phospholipid bilayer allows for the movement of various proteins and other molecules within the membrane, facilitating key functions such as signaling and transport. The other biomolecules play important roles in the cell but do not primarily define the structure and function of the membrane. Proteins, while integral to many processes within the membrane, rely on the structural framework provided by phospholipids. Carbohydrates are associated with cell recognition and communication but do not form the structure of the membrane itself. N